Western Michigan University ScholarWorks at WMU
Master's Theses Graduate College
12-1978
Chromosome Behavior and Cytokinesis of Nezara Sp. and Lygaeus Sp.
Mohamed Barka Marwan
Follow this and additional works at: https://scholarworks.wmich.edu/masters_theses
Part of the Biology Commons
Recommended Citation Marwan, Mohamed Barka, "Chromosome Behavior and Cytokinesis of Nezara Sp. and Lygaeus Sp." (1978). Master's Theses. 2142. https://scholarworks.wmich.edu/masters_theses/2142
This Masters Thesis-Open Access is brought to you for free and open access by the Graduate College at ScholarWorks at WMU. It has been accepted for inclusion in Master's Theses by an authorized administrator of ScholarWorks at WMU. For more information, please contact [email protected]. CHROMOSOME BEHAVIOR AND CYTOKINESIS OF NEZARA SP. AND LYGAEUS SP.
by Mohamed Barka Marwan
A Thesis Submitted to the Faculty of The Graduate College in partial fulfillment of the Degree of Master of Arts
Western Michigan University Kalamazoo, Michigan December 1978
Reproduced with permission of the copyrightowner. Further reproduction prohibited without permission. ACKNOWLEDGMENTS
First of all, I wish to express my sincerest thanks and deepest appreciation to Dr. Gian C. Sud for his constant and tireless guidance, counsel, and supervision throughout the progress of the study. He gladly gave up his vacation
time in order to accompany me to Libya for the purpose of a collection trip. He was of utmost help during the pre paration of the material, slides, and study of the prepared slides. I must also acknowledge his extremely valuable assistance and cooperation in the preparation of this manuscript.
Further, I am thankful to Dr. William C. Van Deventer and Dr. Clarence J. Goodnight for consenting to serve on my Dissertation Committee. Their suggestions during the
oral examination were extremely beneficial. I am also thankful to the Department of Biology, Western Michigan University, for providing me with the facilities necessary to carry out this work.
I will be amiss in my duty if I did not express a very deep sense of thanks to the University of Al-Fetah, Tripoli-Libya, for providing me with the most generous help
ii
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. during my visits to Libya. They not only provided me with the needed laboratory space during the summers, but also placed their entire support staff and store facilities to carry out my work. For this, I am deeply indebted to the Dean of the Faculty of Science, Dr. Tahar Rabte, and every other faculty member and administrator at the University of Al-Fateh.
Finally, I am deeply grateful to the Government of Libya, and the staff of the Cultural Section of the Embassy of Libya in Washington, D. C., for providing me
with the necessary financial support to complete my education. It is because of Libya's long range dedi cation and commitment to higher education, and generous
support to the students that I have been able to complete this work. I am ever so humble and grateful.
Mohamed Barka Marwan
iii
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. INFORMATION TO USERS
This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted.
The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction.
1.The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity.
2. When an image on the film is obliteraterl with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame.
3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again - beginning below the first row and continuing on until complete.
4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced.
5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received.
University Microfilms International 300 North Zeeb Road Ann Arbor, Michigan 48106 USA St. John’s Road, Tyler’s Green High Wycombe, Bucks, England HP10 8HR
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1312135
| MARWAN, mohamed barka CHROMOSOME BEHAVIOR AND CYTOKINESIS OF NEZAKA SP. AND LYGAEUS SP.
WESTERN MICHIGAN UNIVERSITY, M .A., 1978
University Microfilms International 300 n. z e e b r o a d, a n n a r b o r, mi 48105
© 1978
MOHAMED BARKA MARWAN
ALL RIGHTS RESERVED
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS
CHAPTER PAGE
I INTRODUCTION...... 1
II PREVIOUS LITERATURE...... 4
Sex-chromosomes...... 4
Phenomenon of Reduction...... 10
Cytokinesis...... 16
III MATERIALS AND TECHNIQUES...... 23
Materials...... 23
Techniques...... 24
IV RESULTS...... 27
Spermatogonia...... 28
Meiosis...... 31
Reductional phase...... 31
Equational phase...... 43
V DISCUSSION...... 46
Chromosome Behavior...... 46
Cytokinesis...... 51
VI SUMMARY...... 57
VII APPENDIX 1 ...... 58
VIII APPENDIX II...... 63
IX LIST OF PLATES...... 68
X BIBLIOGRAPHY...... 116
iv
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. INTRODUCTION
The order Hemiptera (class Insecta) has been a
favorable material for chromosome-cytology investigations.
Wilson (1905, 1906, 1909, 1912), Browne (1916), Hughes-
Schrader and Schrader (1961), Ray-Chaudhry and Manna (1952),
and Sud (1955) are among those who have done extensive
work on the order, and they are of the view that usually
the XY-type of sex-chromosomes are present in it.
Wilson (1905, 1906, 1909, 1912), and Manna (1951)
describe XY-type in four species of the genus Lygaeus.
They reported that the first division is reductional
for the autosomes but equational for the sex-chromosomes,
and the second division is just the reverse, being
equational for the autosomes and reductional for the
sex-chromosomes.
Ray-Chaudhry and Manna (1952) described a very
unique case of meiosis in Dysdercus koenigii. In this
species, both the meiotic divisions are reductional for
the sex-chromosomes, which are of the XY-type. Sud (1955),
working on Dysdercus cingulatus, confirmed their obser
vations, and reported that there is no meiosis II for the
sex-chromosomes. As a result, fifty per cent of the sperms
are without X or Y. Dysdercus cingulatus has sixteen
chromosomes, fourteen plus the XY.
1
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2
Besides the divisional behavior of the sex-chromosomes,
many studies have concentrated around their attachment to
the spindle fibers. Battagli (1956), in Dysdercus koenigii
and Parshad (1957), in Pyrrhoplspus posthumus, described
the presence of two X-chromosomes, X^ and X2, both of which
became attached end to end at the first anaphase. However,
in Dysdercus intermedius, Ruthmann and Dahlberg (1976),
found that this attachment is delayed until anaphase II,
possibly due to the persistance of fine, thread-like
connections between sister chromatids throughout anaphase.
Hughes-Schrader and Schrader (1961), described meitotic
chromosomes of Heteroptera which are designated as holo-
kinetic since the chromatids lie in one plane on the
metaphase plate, and daughter chromosomes move parallel to
each other at anaphase. Holokinetic chromosome behavior
is related to "diffuse kinetochore" condition, in which
the spindle fibers are attached along the whole poleward
surfaces of the chromosomes.
Several other studies also suggest that the chromo
some behavior in Hemiptera is of great interest, not only
from the standpoint of division, but also in terms of their
attachment to the spindle fibers and anaphase movement.
The present study deals with two species of Hemiptera
collected in Tripoli, Libya, with a view to understanding
the chromosome behavior in these species, and also to the
matter of cytokinesis. Extensive survey of the literature
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 clearly indicates that not much attention has been given
to the matter of cytokinesis— its origin, its relationship to the spindle fibers, or the chromosome movement.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. PREVIOUS LITERATURE
Sex-chromosomes
The sex-chromosomes were seen, and in some cases
carefully described, long before their relation to sex-
determination was suspected. Henking (1891) described
a "peculiar chromatin element" in the Hemipteran pyr-
rhocoris. In the second spermatocyte division, this
element first lags behind the separating anaphase chromo
somes and then passes undivided to one pole, while all the
other eleven chromosomes are equally dividing. He notes
that "the sperms are of two numerically equal classes,
distinguished by the presence or the absence of the
chromatin element in question." This "peculiar chromatin
element" is labeled "X". The general implications of his
brief account seem to be that this body is a chromosome.
However, its chromosomal nature was not fully established
in Pyrrhocoris until long afterwards.
All the essential features of Henking's description
were subsequently confirmed in other insects by other
observers such as Paulmier (1899) in the Hemipteran Anasa
tristis, Montgomery (1901) in Protenor, and Sinety (1901),
in the Phasmids Orphania and Dixippus. These chromosomes
have been described by many names such as: "special chrom
osomes" (Sin£ty, 1901), "odd chromosome" (Montgomery, 1901),
4
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. "accessory chromosome" (Me Clung, 1902), "idio-chromosome"
(Wilson, 1905), "heterotrophic chromosome" (Wilson, 1906),
and "monosome" (Montgomery, 1906). Montgomery also desig
nated this chromosome as "chromosome X" in the case of
Protenor. However, the specific term X-chromosome was
suggested by Wilson (1909).
In the meantime a second, and slightly more comp
licated, type of sex-chromosome was described by Montgomery
(1898 and 1901) in various Hemiptera under the name of
"chromatin-nucleoli," but their real nature was not suspect
ed at that time. Although the term X (or Y) chromosome is
used widely, perhaps the most widely employed other term
for these chromosomes is the "accessory chromosomes"
(Me Clung, 1902).
The term accessory chromosome, however, has been used
extensively through the early part of this century for
those chromosomes which are additional to both the auto
somes and the sex-chromosomes. In Gryllotalpa vulgaris,
Voinov (1912) found an accessory chromosome in addition
to the unequal pair of chromosomes. He labeled this
chromosome as the M-chromosome. In meiosis I, the X-
chromosome is constricted into three, one going to one
pole and the other dyads going to the other. At the second
meiosis, all these parts divide. His findings may be
summarized as follows:
1. Four dyads plus M-chromosome plus a bivalent
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 6
plus Y.
2. Four dyads plus M-chromosome plus an accessory
chromosome plus X.
3. Four dyads plus M-chromosome plus a bivalent
plus X.
4. Four dyads plus M-chromosome plus an accessory
chromosome plus Y.
Charlton (19 21) continued to use the term idiochromo-
somes to describe the sex-chromosomes in Lepisma domestica.
Me Clung (1901, 1902) was the first to suggest that
the X-chromosome is concerned with sex determination. He
emphasized a parallel between the two equal classes of
sperms differentiated by the X-chromosome, and the two
equal sexual classes of adults. He was thus led to the
hypothesis that this particular chromosome is the "sex
determiner;" but the actual proof of this was not produced
until a few years later.
The insects show many variations of cytological
detail with regards to the sex-chromosomes, which may be
grouped in different classes as the following:
1. The simple XO-XX or the Protenor type.
2. The simple XY-XX or the Lygaeus type.
3. The X-complex or the Compound type.
4. The linkage of sex-chromosomes with autosomes.
At this point, a brief historical review of the lit
erature on sex-chromosomes is in order. In 189 8, Montgomery
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. stated that the male Hemipteran should have one more chromo
some than the female. Earlier, he had described two small
"chromatin nuclei" in Nezara hilaris, without realizing
the significance of the two bodies. However, he continued
to insist that the male had an extra chromosome in all
species. Me Clung (1899) tried to clarify Montgomery's
hypothesis by stating that the X bearing class of sperms
were the male producing sperms. Montgomery's hypothesis
was adequately supported by Gross (1904, 1907), who was
working on Eyromastes marginalis.
It was in 1905 that Wilson, working on Nezara
hilaris, described that the sex-chromosomes are not always
odd. Instead, he stated that there are two types of sex-
chromosomes, which he labeled X and Y. In a way, Wilson
pioneered a detailed study of the sex-chromosomes over a
number of years. Working on a large number of species,
both from insects and other animals, he discovered that
the sex-chromosomes are usually lined in the center of a
"metaphase ring" formed by the autosomes. He paid a great
deal of attention to the matter of their distribution to
the sperm nuclei. Also, it was he who proposed a possible
connection of these chromosomes to sex. He worked on
Hemipterans Lygaeus, Co.enus, Podisus, Euschistus.
Stevens (1905) showed that in the beetle Tenebrio
that the XY pair of the male is replaced in the female by
an XX pair. It was Stevens (1908), studying the meitotic
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8 cells of Dermatopia hominis, who described that the Y
chromosome was a little shorter than the X chromosome.
Working with a relatively large number of species, he
established that the X and Y pair was similar to that of
Dermatopia hominis.
Wiison, in his earlier papers (1905, 1906), had
called the Y chromosome the "small idiochromosome" and X
the large "idiochromosome," but later (1909) he proposed
the terms Y- and X-chromosomes in the interest of simplic
ity. Of course, sex-chromosomes of this type had been
seen earlier by Montgomery (1898, 1901) in a number of the
Hemiptera and described by him under the name of "chromatin
nucleoli" without recognizing their relation to sex.
In a paper published in 1911, Wilson re-examined the
chromosomes of Nezara hilaris. He found that, because of
its smaller size, at times, the Y-chromosome was obscured
by the X-chromosome at the metaphase ring stage. This is
why, at times, some insects show XO type rather than XY
type.
Attention to the chemical behavior of the sex-chromo
somes was paid by Payne (1909, 1910, 1912). In 1909, he
worked out the spermatogenesis in Gelastocoris peculation,
Sinea diadema, Acholla multispinosa, and Aribus cristatus,
and described that, throughout the growth period, the sex-
chromosomes evince a marked heteropycnosos.
Payne (1909, 1910) described that in Acholla ampliata,
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. a genus related to Sinea, the X-complex consists of three
small, equal components; in A. multispinosa of five, three
of which are small, equal components. The whole group of
X-chromosomes is "opposed by a very large Y-chromosome."
Also in (1910), he found that the Hemipteran Acholla
multispinosa has a Y which appears to be considerably
larger than X, a finding similar to the one made in
Drosophila melanogaster (Bridges, 1913, 1916), and Pnison-
tis modesta (Payne, 1912). But, these observations seem to
be exceptional.
Payne (1912), working on Reduvidae, described an X-
complex of five components and the Y in Sinea ribye.
This is a brief history of various terms that have
been proposed for the sex-chromosomes and their relation
ship to sex-determination. Appendix I describes in summary
form the evolution of the work done on sex-chromosomes. It
indicates the authors and the species upon which they
worked, the type of sex-chromosomes, and any special feat
ures that they may present. It is important to note that
most of the special features of the sex-chromosomes are
related to heteropycnosis, their fragmentation, presence
or absence of the Y-chromosome, their relationship to each
other, and their relationship to the spindle fibers and
the anaphase movement.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 0 Phenomenon of Reduction
It is now universally accepted that meiosis actually
consists of two phases, the reductional phase and the
equational phase, also called meiosis I and meiosis II,
respectively. The reductional phase is extremely extensive
and elaborate, primarily because of the changes that the
nucleus undergoes through the interphase and the prophase.
It is during these phases that the pattern of pairing, or
synapsis, of the homologous autosomes and the sex-chromo
somes is accomplished. Further, it is due to this homolog
ous pairing that the number of chromosomes is reduced to
a haploid number at the end of meiosis I.
Prophase I received attention early from such
workers as Winiwarter (1901), Wilson (1912), and Me Clung
(1917). Winiwarter concentrated on animals, although his
findings are equally applicable to the plants. Work of
Me Clung was extensive on the Orthopteran germ cells.
Historically, the following stages were included in
the prophase, which begins at the completion of the final
Gonal Telophase (Wilson, 1928). However, all the histor
ical descriptions of the stages described below are not
necessarily accurate.
1. The Resting or Net-Like Stage
It is of a relatively short duration in which the
chromosomes are temporarily lost to view. This is wide
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. spread both in plants and animals. This is actually the
Interphase I, after which Prophase I begins.
2. The Prochromosome Stage
During this stage, the chromosomes are totally un
identifiable, appearing only as massive bodies scattered
throughout the nucleus. However, the appearance of these
massive chromosomal bodies varies from species to species,
particularly as observed in Orthoptera and Coleoptera.
3. The Unravelling Stage
During this stage, each chromosome resolves itself
into closely convuluted or irregularly coiled fine threads
Again, the behavior of individual chromosomes, including
the sex-chromosomes and the M-chromosomes, may vary from
species to species.
4. The Leptonema or Leptotene Stage
This is a fundamental and all but universal stage,
from which all later stages take their point of departure.
The nuclear substance becomes resolved into delicate
threads which typically show no sign of longitudinal
splitting. The evidence seems to indicate that, in the
animals, the leptotene spireme is not continuous but con
sists of separate segments. Further, some cases have
clearly shown that the leptotene threads are diploid in
numbers, meaning that the bivalent formation has not yet
occurred.
The forgoing four stages are prepratory to the
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 2 synapsis or pairing of the chromosomes and are often
designated as pre-synaptic or pre-syndesic stages. The
stages that follow are basically the synaptic stages.
5. The Synaptic Stage
It is during this stage that the actual association
or conjugation of the chromosomes (leptotene threads)
occurs, forming bivalents. The process is designated as
synapsis or syndesis. Several other terms have been used
to describe this process, including those used by Wini
warter (1901) and Gr&goire(1910). However, a detailed
discussion of different terms used in the literature is
not necessary.
In higher plants and most of the Arthropods, and in
some invertebrates, the leptotene threads commonly show no
polarization. Instead, they become massed together into
a more or less dense, intensely straining knot, usually
situated to one side of a nuclear cavity, often enclosing
the nucleolus. This is the so-called contraction, or
synizesis stage, which greatly increases the obscurity of
the nucleus. This is conspicuously present in Hemiptera
and Onodonota but is conspicuously absent in most
Orthoptera.
Although there have been questions regarding synapsis,
the evidence overwhelmingly supports the observation that
it is during synapse that the bivalent formation occurs.
In any event, the polarized threads progressively thicken
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 3 and shorten by the process which begins at their polar
(free) ends and proceeds toward the opposite pole. Thus,
the polarized, thick threads are called pachytene stage,
while the anti-polar, thin threads are the leptotene
threads. This stage also has been called the amphitene
stage by Janssens (1901).
6. Post-synaptic Spireme (also called Auxospireme)
The threads are shorter, thicker and haploid in
number.
7. Diffused Stage
This is a rather vague stage in which the nucleus
recedes more or less into the condition of a resting
nucleus. The diffused stage is much more common in the
oocytes than in the spermatocytes. In some species, such
as urodeles, various Orthoptera, copepods, platodes, etc.,
the diffused stage is hardly distinguishable.
8. The diffused stage may be followed by another
stage which has been arbitrarily termed Second Synezisis
or Contraction Figure. However, its distribution in the
animal kingdom is rather limited.
9. Diakinesis
This stage has been labelled as the true prophase by
some of the investigators. Others have called it as the
final stage of the so-called resting phase. But, it is a
stage when the cell is well along into the prophase.
In this stage, the bivalents have assumed their final
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 4 form by a rapid process of condensation. Their quadri
partite or tetrad structure is evident. The tetrads
are unmistakably separate bodies, commonly peripheral in
position, and haploid in number. Some investigators have
divided the stage into three sub stages:
a. Early diakinesis
In the early diakinesis, the bivalents appear in the
form of separate more or less elongated spirene-like
threads, longitudinally double or quadripartite.
b. Middle diakinesis
In the middle diakinesis, there is a pronounced
shifting of the chromatids. The bivalents are rapidly
condensing, and many of the characteristic forms of the
tetrads such as c-rings, double crosses, transverse tetrads,
etc., are highly visible.
c. Late diakinesis
In this final substage of diakinesis, the bivalents
have completely condensed into definite massive bodies,
the chromosomes.
The forgoing account is generally applicable to the
resting phase and the prophase found throughout the entire
animal and plant kingdom. However, there are individual
variations that occur from one species to another. Perhaps
it is important to describe some of the variations at this
point. Accordingly, an elaborate amount of data is included
in Appendix II, which pays particular attention to all
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 5 variations which occur from the arbitrarily established standard sequence of stages as described above. It may be added, that the extensive researches of the last twenty-five years have clearly established that the interphase stage is indeed of long duration. Further,
it has the greatest amount of biochemical activity of any other stage (Ris, 1976).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 6
Cytokinesis
At the completion of telophase, a cell divides into
two daughter cells. The physical process of cell division
in animals was discovered early in "the segmentation of the
animal eggs", by Pr&vost and Dumas (1824), and soon after
wards it was discovered in the lower plants by botanist
Mohl (1835). But, its significance was fully recognized
only after the postulation of the Cell Theory, especially
as a result of the work of Remak (1850-1855) and Virchow
(1858). The mechanism of cell-division was not precisely
investigated until long afterwards, but Remak in 1855
showed that the process involves a division of both the
nucleus and the cytoplasm.
It became apparent rather early in the history of cell
division that the process of cell division, or cleavage,
was different in the animal cells as compared to that in
the plant cells.
Strasburger (1875) first observed cleavage by cell-
plate formation in the cells of higher plants. With a few
exceptions, these cells divided without the appearance of
an equatorial furrow; instead, they divide by the formation
of a protoplasmic partition, wall or cell-plate, which
first appears in the equatorial plane of the spindle and
extends itself completely across the cell at right angles
to the spindle-axis. At first, the cell-plate is to be
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 7 single, but, sooner or later, it splits into two parallel
plates, between which appears a new cell wall. This new
cell wall extends across the whole cell and cuts it in two.
Sharp (1911) stated that in the late telophase, fol
lowing the reconstruction of the daughter-nuclei, the cell
plate makes its appearance in the form of a series of thick
enings in the connecting fibrillae of the spindle in the
equatorial plane. At this time, the spindle becomes con
vex in the equatorial region so as to assume more or less
of a barrel-shape in which condition it is often called
the phragmoplast. In later stages, the phragmoplast
undergoes further lateral extension, apparently by the
continual addition of new fibers outside the limits of the
original spindle, until it extends completely across the
cell in the equatorial plane. The equatorial thickenings
of the fibers, at first separate and confined to the axial
region of the spindle, extend progressively as the phrag
moplast widens, and finally reach the periphery. At the
same time, they fuse to form a continuous cell-plate, a
process which begins in the axial region, before the phrag
moplast has reached the periphery, but finally extends
across the whole cell. Meanwhile, the spindle-fibers be
gin to disorganize and finally disappear; and this process,
too, commonly begins in the axial region and often long
before the cell-plate has reached the periphery, while the
mere peripheral fibers are still intact.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 8
Of course, much work has been done in recent years to
fully understand the process of cell division in the plant
cells. In the present study, however, attention is focus
ed upon the process of cell division in the animal cells.
It is clear that the animal cells divide by the pro
cess of constriction as opposed to plate formation. Guig-
nard (1897) first noted the constriction which occurs in
division of the anastral type of cells. This process was
then studied extensively in magnolia by Farr (1918). As
a result of their thorough and extensive work, it was
proposed that cleavage by constriction appears in the one-
celled organisms, both plants and animals, but it has the
"greatest advantage in the cells of higher animals, par
ticularly in the cleavage of the animal ovum." It is now
well known that the anastral cleavage is a characteristic
of marine invertebrate eggs, the spherical cell divides to
give two equal blastomores.
Conklin (1902) suggested that as the cleavage-furrow
advances towards the center of the cell, the spindle is
usually constricted at its middle point and thus, often
assumes an hour glass shape. When the furrow advances
more rapidly from one side, the center of the spindle is
often bent more or less sharply at this point, but this
result is clearly not due merely to the advance of the
furrow, but also to the telokinetic movements of the
asters (or spheres), and daughter-nuclei towards the sur-
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 9 face. These movements probably form part of the more
general vertical movement of the protoplasm and hence
probably are traceable likewise to the equatorial increase
of surface tension at this time.
As indicated above, it was established in the early
part of this century that the animal cells divide by
constriction, described by different names.
Some of the terms used to describe the physical divi
sion of a cell into two are: furrowing, cleavage, cyto
kinesis, etc. The matter of the plane along which cleavage
progresses has been of considerable interest. In recent
years, however, great deal of attention has been paid to
those biochemical aspects which initiate cleavage as well
as those which bring the actual process into being.
The term cytokinesis was first used by Whitman (1887)
to designate the associated changes which take place in the
cytoplasmic cell-body. Sometimes, it is difficult, however,
to draw any definite line of distinction between the
nuclear and cytoplasmic activities, e. g., the formation
of the spindle.
Much research has been done on cytokinesis involving
such questions as:
1. What initiates cleavage:
2. What are the biochemical and physical aspects of
cytokinesis?
3. What is the relationship of cleavage-constriction
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 0
to the spindle body?
4. Does the constriction begin and progress evenly
at the equatorial circumference of the cell?
These are only a few of the questions that have been
raised in the literature.
Chambers and Kopac (1937), working on Echinoderm eggs,
stated that the cleavage furrow is completely displaced by
the mitotic apparatus from the equatorial plane.
Inspite of some of the exceptional observations, such
as that of Chambers and Kopac, there seems to be a consensus
of opinion that the constriction begins at the circumfer
ence of the cell, and progresses evenly until the cell is
completely pinched off into two. Further, the plane of
progress of the constriction is at right angles to that
of the spindle fibers.
Marsland (19 50) proposed that the furrowing potency
in animal cells depends upon the structural state of the
plasmagel. It enhances the contractile capacity of a
strongly gelated cortical layer of cytoplasm, especially
in the furrow region. Recent workers indeed tend to agree
generally that the decisive role in cytokinesis is played
by the cortical plasmagel layer of the cytoplasm. However,
there is no agreement as to the precise mechanism of the
furrowing process. In fact, two opposite viewpoints are
currently held.
First, the cell membrane is pushed down in the deve-
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 1
loping furrow by a process of "growth" (Schechtman, 19 37;
Chabmers, 1938), or of expansion (Swann, 1952; Mitchison,
19 52) occurring in the cortical protoplasm.
Second, the cell membrane is pulled inward into the
furrow by a contraction of the subjacent plasmagel in the
equatorial region, (Lewis, 1942, 1951).
In recent years, attention has focussed on the ultra
structure of cytokinesis. Some of the findings have been
interesting. Kessel and Beams (1963), and Stay (1965),
stated that the developing furrows and furrow canals are
the coated pits found attached to the egg surface before
cytokinesis begins and to the furrows and furrow canals
themselves during cytokinesis. These pits are reminiscent
of structures of similar morphology which have been seen
in oocytes. In these cases, the coated pits have been
involved in micropinocytosis.
The theory of Rappaport (1965, 1969) which explains
localization of the cleavage furrow in sea urchin eggs,
offers an explanation for cleavage furrow formation in
Drosophila. According to Rappaport, the furrow forms as
a result of the combined influence of two asters and the
distance between the asters and the surface are critical:
If one distance is increased experimentally, the other
must be decreased in order that a furrow be produced be
tween the two asters. This leads to the conclusion that
furrowing of the membrane takes place at the point of
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 2
overlap of the influence of two asters.
Contractile microfibrils have been implicated as
agents involved in cleavage in several egg types (Arnold,
1969; Goodenough et.al, 1968; Schroeder, 1968; Selman and
Perry, 1970; Szollosi, 1968) and in cell division (Schroed
er, 1970) .
Fullilove and Jacobson (1971) and Mahowald (1963),
observed that the contractile system existed in the Dros
ophila egg just beneath the surface membrane and oriented
in an hexagonal array at the sites of cleavage furrow
initiation, the constriction of the fibers could be res
ponsible for the flattening of the surface membrane sur
rounding the nuclei, with the resultant "bunching up" of
the surface above the nuclei into hillodes and villi.
Further contraction might be the force responsible for the
initial movement of the furrow canal into the cytoplasm,
thereby initiating cleavage.
They have observed fibrillar material near the furrow
canals, although such a network has not yet been demonstra
ted beneath the flattened surface membrane prior to cyto
kinesis.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. MATERIALS AND TECHNIQUES
Materials
At the beginning of the present study, it was decided
that the specimens belonging to the order Hemiptera would
be collected from Libya. Accordingly, a collection trip
was made to Libya in the summer of 1976. Lygaeus sp. were collected mostly in Tagura, about
twenty miles east of Tripoli. Large numbers of these
insects can be found in alfalfa, corn, or wheat fields
particularly in the months of June, July, and August.
However, the number of insects seems to be very low from
September on. Nezara sp. were collected from fields around the
University of Libya in Tripoli. Alfalfa, tomato, and green
pepper fields, and olive trees were found to be an extreme
ly good source of these insects. Once again, the number of
these insects seems to be at their peak from May through
September, although they could be found in scarce numbers
throughout the year. Freshly collected insects were brought to the labora
tory for dissection of insects and preparation of desired
material. The laboratory was provided by the Department
of Zoology, University of Libya (University of Al-Fateh),
Tripoli, Libya. The present work was done on the testes of these two
insects. In both species, the female is bigger than the
23
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 4
male.
Technique
The insects were dissected in standard saline solu
tion. In Lygaeus sp. a pair of white, triangular testes,
invariably with several lobes, were separated. Each testis
is about 1.5 mm. long. In Nezara sp. there is a pair of
red colored testes, each about the size of a pinhead. The
testes were cut into smaller pieces, which were quickly
transferred to the appropriate fixatives.
Light microscopy
The testes were fixed in three different fixatives,
Bouin's fluid, Champy's fluid, and Carnoy's fluid, for
graded time series ranging from six to eighteen hours.
In Bouin's fluid, the material was fixed for a period
ranging from six to twelve hours; twelve-hour fixation was
found to be excellent. In the Champy's fluid, the material
was fixed from six to eighteen hours; eighteen-hour fix
ation was found to be excellent. In Carnoy's fluid, the
material was fixed from six to twelve hours; six-hour
fixation was found to be excellent. After fixation, the
material was washed under running water for about twenty-
four hours.
Then, it was dehydrated through a series of alcohol
changes, and embedded in paraffin wax (m.p. 54° C). Blocks
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 5
were made with two metal "L's" with a metal base plate for
embedding specimens. Trimming of the blocks was done
manually. Rotary, precision, AO was used for cutting.
Sections were cut at a thickness between 5 - 8 microns (u).
A 6u thick section gave excellent results. The sections
were mounted on slides, and spread in warm water bath at
37° C. Slides were left to dry at room temperature.
Standard staining technique was followed (Heidenhain,
1908). After treating the slides in Xylol for one hour,
to remove the paraffin wax, they were taken through a
graded series of alcohol as follows:
Absolute alcohol. . . .10 minutes
90 % " . . . .20 minutes
70 % "* ... .1 hour or overnight
50 % " . . . .1 hour
30 % " .... 1 hour
The slides were stained in 5% iron haematoxylin.
4% iron-alum mordant was used to fix the dye. The slides
were then differentiated in 2% iron-alum.
After differentiation, the slides were dehydrated
through a graded series of alcohol as follows:
30 % alcohol. . . .30 minutes
50 % " .... 30 minutes
70 % " ... .1 hour or overnight
90 % " . . . .2 hours
Absolute " .... 1 hour
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 6
If needed, the slides were left in 70% alcohol for
overnight.
They were mounted in clear-mount and dried in an
oven at 370 c. for 24 hours. Dry clear-mount was removed
with a blade and the slides were cleaned with Xylol.
The slides were studied under the Zeiss photomicro
scope Pol. Diagrams were drawn with the help of a Camera
Lucida, while the pictures were taken with a mounted
camera. The total magnification of 1,250' X> could be"
obtained with this microscope.
Electron microscopy
Testes were fixed in 25% glutaraldehyde for one hour
at 4° C. for both species— Nezara sp. and Lygaeus sp.
They were dehydrated and embedded in Epoxy in gelatin
capsules, which were left in the oven at 60° C. for 48
hours. They were then removed and labeled.
Capsules were trimmed under a light microscope.
Ultra microtome Mark 2 Huxley-pattern type 5 2271 was
used for cutting sections 16 nm. thick. Sections were
mounted on copper grids, and they were stained with 5%
uranyl acetate and lead acetate. Cells were observed
under Elmaskop IA microscope with a magnification between
8,800 X to 20,800 X . .
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. RESULTS
The present study focussed attention on chromosome
behavior and cytokinesis of two species of Hemiptera,
Nezara sp. and Lygaeus sp., with the help of Zeiss Model
RA - 38 microscope, and Elmaskop IA electron microscope.
However, most of the results reported below are from
Nezara sp.
The lobes of the testes are covered by a sheath of
connective tissue, called tunica albuginea. The testis
is rounded at the anterior end, gradually tapering toward
the posterior end. The anterior and posterior ends are
connected with one another through a vas-deferens.
A careful examination of the slides showed that,
although the cross-sections as well as the longitudinal
sections of the testes were full of dividing cells, the
longitudinal sections showed a better topographic arrange
ment of the cells.
The anterior portion of the testes is filled with
spermatogonia, with a gradation of meitotic stages in the
posterior region. That is, immediately after the anterior
end, there is a heavy concentration of primary spermato
cytes and the very posterior end of the testis is filled
only with spermatozoa. As a matter of fact, even at the
middle portion of the testis, there is an extremely heavy
27
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 8
concentration of spermatids and mature sperms. The dis
tribution of cells, on the basis of their divisional phases,
has been used as a criterion to determine the time lapsed
in each stage. This is described later.
No sertoli cells were found in the seminiferous tub
ules, as has also been suggested by Yasuzumi, Tanaka, and
Tezuka (1960).
Spermatogonia
The average germ cell in the testis is ten microns
(10 u) in diameter. The division of these cells is by
normal mitosis. A brief description of the final mitosis,
leading to the formation of spermatogonia, is in order.
A. Resting stage or interphase
The cell is round with a centrally located round
nucleus. Usually, there is a clear space around the
nucleus (plate I, figure 1). The darkly stained chromatin
granules seem to be distributed evenly in the nucleus.
However, even at this stage, there appear two dumb-bell
shaped heteropycnotic bodies. Heteropycnosis is positive
related to the nucleolus. One of these bodies is larger
than the other and they are the sex-chromosomes of the
XY type.
B. Prophase
The prophase stage is normal with roundish but irreg-
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 2 9 ularly shaped chromosomes in the nucleus. A careful
examination of the cells, studying the slides at different
depths under the oil emersion lens, shows that there are
fourteen chromosomes. This number will be later verified
at the metaphase I plate in a polar view. The centriole
divides into two each developing astral rays around it, and
they gradually begin to move away from each other. The
longitudinal axis of the spindle fibers is at right angles
to the original position of the centriole.
The end of prophase is indicated by the disappearance
of the nuclear membrane, wherein the chromosomes are still
surrounded by the clear space described above (plate I,
figures 2 and 3).
C. Metaphase
Metaphase is indicated by the disappearance of the
nuclear membrane and the appearance of the spindle fibers.
The chromosomes arrange at the equator of the spindle body.
Inasmuch as the spindle body, or the spindle fibers,
has been of great interest to many investigators in recent
years, an attempt was made to study the spindle fibers
of this insect under the electron microscope. However,
further work is needed to describe the ultrastructure of
the spindle body.
A few cells were found in a polar view, clearly
indicating the arrangement of the chromosomes, wherein
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 0
there is a ring of twelve autosomes, with the two sex-
chromosomes, X and Y, in the middle (plate I, figures 4
and 5). However, a better count of the number of the
chromosomes is found at the metaphase I plate (plate II,
figure 5).
D. Anaphase
At the anaphase stage, the rod-like chromosomes are
arranged parallel to the longitudinal axis of the spindle
fibers (plate II, figure 6). The movement of the chromo
somes along the spindle fibers is normal and concurrent.
In other words, no difference in the timing of movement
of any of the autosomes or the sex-chromosomes was found.
In the literature it has been described frequently that
the sex-chromosomes lag behind the autosomes in the ana
phase stage. However, that was not the case in this par
ticular species.
E. Telophase
As the chromosomes reach near the astral rays, they
begin to condense into a common mass (plate III, figures
7 and 8). The spindle fibers begin to elongate assuming
a dumb-bell-shape as the telophase progresses.
After the chromosomes have reached the two poles,
the decondensation of the mass of chromosomes begins
(plate III, figure 9), and the nuclear membrane begins
to reappear as the cell enters cytokinesis.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 1
F. Cytokinesis or cleavage
An extremely interesting mechanism of cleavage or
cytokinesis was found in this species. The cleavage, or
furrow, of the cell begins at one end and gradually pro
gresses to the other as shown in plate III, figures 8 and 9.
Plate IV, figure 10, shows a magnified view of the pro
gression of the groove at one end of the cell.
While the cell is beginning to cleave at the one end,
progressing toward the other, resembling like a semi
dumb-bell, an equatorial plate is laid down at the middle
of the cell (plate III, figures 7, 8, and 9). This is
an interesting observation because, at this stage, the
cell resembles a plant cell. Thus, cytokinesis or clea
vage, is completed by a two fold process: cleavage at
one end accompanied by the progressive outward growth of
the equatorial plate.
Meiosis
As is now well known, meiosis has two phases, the
reductional phase and the equational phase, alternately
described as meiosis I and meiosis II. Each stage of
meiosis I and meiosis II is accordingly labeled as stage
I or stage II.
I. Reductional phase
A. Resting Stage I or Interphase The cells in resting stage, are the primary spermato-
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 2
cytes, which are a bit larger than the spermatogonia. On
the basis of measuring 100 cells, their average diameter
was found to be 11.8 microns. Further, out of 920 cells
counted at random, 302 cells were found in the resting
stage. It would seem, therefore, that the Resting Stage
I takes a major portion of the time required to complete
meiosis I. (Graph I, Table II).
In the resting stage, the cytoplasmic layer is
relatively thin, surrounding a round nucleus. The nucleus
contains a diffused and scattered mass of chromatin mat
erial, (plate V, figure 11, and plate XXIV, figures 51
and 52). The bean-shaped nucleolus is usually located
toward one side of the nucleus (plate V, figure 12). It is
invariably surrounded by light ground substance, (plate V,
figure 13). Scattered in the nucleus are heteropycnotic
knobs (plate V, figure 14), clearly shown under the electron
microscope (plate XXIV, figure 52) .
B. Prophase I
1. Leptotene stage:
As is now well known, the resting stage is indeed
highly active in terms of biochemical activity including
synthesis. However, the end of the resting stage is
marked by the formation of thread-like structures in the
nucleus called the leptotene threads (plate.'V, figure 15).
The leptotene threads gradually increase in density as the
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. without prohibited reproduction Further owner. copyright the of permission with Reproduced
C o v x >c^ vqA o f X q 2 26o 0 4 2 Mo 0 2 2 o o 3 3£> ito Mo too 20 40 So 0 o
. t n I I . I H .I p CoocAeA A e A c o o C ► GyVG^Vx I. ~^V\£ 'T^Anovv^n^ \>&vGyVG^Vx : ~^V\£ 'T^Anovv^n^ I. t * j s e c t c \ W o V e ^ «.
1 . y x c v\vx.nn^o^V v\vx.nn^o^V ^ A . Cyt. l. T l c > s \ ^ C 0 C<^ < C ^ \ a X C 33 3 4
condensation of the chromatin material continues, (plate
VI, figures 16 and 17; and plate VII, figure 18). The
leptotene threads are highly looped and irregular, inter
twined with each other. Each thread has a heteropycnotic
knob at its end (plate VI, figure 17).
The leptotene threads can be clearly seen as indivi
dual units at different depths under the oil emersion lens.
2. Bouquet stage:
As the leptotene threads gradually condense, they
show a tendency to polarize towards the darkly stained,
highly chromatic nucleolus. This polarization continues
until the leptotene threads take a bouquet appearance
arising from the nucleolus (plate VII, figure 19; plate
VIII, figure 20 and figure 21). A careful examination of
the bouquet stage, as shown in figures 20 and 21, clearly
shows that the leptotene threads are not single individual
units at this time. Instead, their nature as double
threads is very much evident. Under high magnification,
it can be seen that, at certain places, these threads are
coiled around one another.
The stage showing the paired leptotene threads has
been called the synaptic stage in which the chromosomal
threads have come together. Some investigators have
described the changes, that occur after the pairing has
been completed, as post-synaptic stages. In any event, the
end of the bouquet stage is indicated by the complete pair-
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 5
ing of the leptotene threads.
3. Zygotene stage:
As the pairing is completed, the threads begin to
condense into irregular bodies and, at the same time, they
begin to lose their polarization toward the nucleolus.
Further, the condensing, irregular bodies begin to pair
on homologous basis, forming what is known as the bivalents.
The pairing of the chromosomes is not uniform throughout
the nucleus as shown in plate VIII, figure 21. Some chrom
osomes are in the advanced stages of pairing while others
are just beginning to do so.
The condensation and shortening of the leptotene
threads continues during the pairing stage. However, at
a time when all the bivalents have been formed, the threads
are still elongated structures. As the pairing is com
pleted, the heteropycnotic knobs of the two components of
the bivalent are almost fused into one another forming one
common heteropycnotic knob. As the formation of the bi
valents continues, the nucleus tends to increase in size
(plate IX, figure 22).
4. Diakinesis stage:
Although the literature describes two more stages
between the zygotene stage and the diakinesis stage, i.e.,
the confused stage and the diplotene stage, the present
study describes all of them under the diakinesis stage.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 36
As the bivalents condense, their outline begins to
become relatively diffused, (plate IX, figure 23) . At
this point in time, two chromosomes seem very closely
opposed to the nucleolus (plate X, figure 24); these are
the sex-chromosomes. The material in which they are
embedded is called plasmosome.
As the condensation of the chromosomes continues,
some of the bivalents begin to show chiasma (plate X,
figure 25). Most of the chromosomes now appear as a
dumb-bell-shaped structure (plate XI, figures 26 and 27);
this stage has been called the diplotene stage. In some
cases, the dumb-bell shape is due to chiasma.
The chiasma frequency of Nezara sp. is 7.80. Chiasma
frequency in the early diakinesis was calculated by divid
ing the total number of chiasma in 25 nuclei by the number
of nuclei counted. The number of chiasma varies from six
to nine per nucleus.
X-ma frequency, per nucleus = Total Number of Chiasmata Number of Nuclei
Total number of nuclei counted = 25.
Total number of chiasmata found = 195.
Xma frequency = 195 = 7.8 per nucleus. 25
Chiasma were found at various positions of the
chromosomes. As the terminal chiasma have been of interest
to the cytogeneticists, the terminal co-efficient was cal
culated as follows;
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 7 Term, coefficient = Number of Terminal Chiasmata Total Number of Chiasmata
Total Number of Chiasmata counted = 195.
Total Number of Terminal Chiasmata = 120.
Term, coefficient = 120 = 0.61. 19 5
Chiasma frequency was then calculated for the late
diakinesis stage by using the formula described above.
Xma frequency per nucleus = Total number of chiasmata Number of nuclei
Total number of nuclei counted = 25.
Total number of chiasmata found = 180.
Xma frequency = 180 = 7.2 25 TABLE I No. of Nuclei Early Diakinesis Late Diakinesis
Xma Frequency Terminal Xma Frequency Coefficient
25 7.8 .61 7.2
The relationships between maximum frequency in early
diakinesis and minimum frequency in the late diakinesis,
and the terminal coefficient, are graphically represented
in Graph II., Table I.
As the process of condensation of the chromosomes
continues, seven distinct bodies can be identified in the
nucleus. Most of the tetrads or the bivalents in Nezara sp.
are rod-shaped, or X-shaped (plate XII, figure 28). How
ever, occasionally some ring chromosomes are also noticed
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 38
~We. ye\S\0'(\‘^cvV^ \oetwe&v\cNvaswmx ' ^ v£ < ^ V & A C ^ S'<\ 6 CUrljJ \ A 6 S>\s> (^V*coivwvvm}CKy\k W e. ^yePVkevvCu \t\ We A c f e ^\V\6SU (V\v\\m^vv) CMvk WeAeywCv<\c^ Co^\CAe.wv-.
&
o■ n
5 5 O- ^ 4
1 X\as ^ve^u.e*\c^ )(wd 2ye^ue*\c^ “femv 0>e^ (Lav ^ T)\aV.\\\eiCi) fifths Di^y\esvs)
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 3 9
which are due to double chiasmata. In some cells, eight
chromosomes are easily identifiable as the pairing between
the X and the Y is not complete. After the chromosomes
are fully condensed, it is usually the end of the diakine
sis stage (plate XII, figure 29).
From this point on, the prophase stage is normal with
all the bivalents clearly visible either as rods, or axes,
or, occasionally, as ring chromosomes. The nuclear membrane
is still intact. Out of a total of 904 cells counted,
273 cells were found in the prophase I stage. (Graph I,
table II), once again suggesting that prophase I is long
lasting.
The nuclear membrane begins to disappear from the
view and the spindle fibers begin to appear. At the same
time, however, on top of the nucleus, the centriole divides
into two, each developing what is known as the astral rays.
The disappearance of the nuclear membrane from view
is the beginning of the metaphase stage.
C. Metaphase I
As is the case in most insects, the metaphase is
highly organized. The spindle body is distinct and the
chromosomes are lined at the equator in a circular manner,
(plate XIII, figure 30 and 31; plate XIV, figure 32 and
33; plate XV, figures 34 and 35).
The arrangement of the chromosomes shows a rather
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 0 interesting phenomenon. In most cases, the homologous
pairing of the X and Y lags slightly behind that of the
autosomes. But in the present insect, the homologous
pairing of the sex-chromosomes is exactly at the same
stage as that of the autosomes. This is clearly indicated
in the figures described above which show a perfect ring of
six bivalents with the seventh bivalent in the center. An
extensive examination of the slides reveals that the Y-
chromosome is either on top of the X-chromosome (as seen in
the upper view) or under the X-chromosome (as seen in the
lower view).
A careful examination of the ring of autosomes
reveals another interesting observation. In almost every
ring, five bivalents are placed close to one another while
the sixth bivalent is relatively isolated, as clearly shown
in plate XIV, figures 32 and 33, and plate XV, figures 34
and 35. This relatively isolated chromosome is one of the
larger autosomes. However, further work is needed, perhaps
with the help of autoradiography, to determine if it is
always the same chromosome which is in this so-called is
olated position in the ring. An examination of serial
sections shows that this relatively isolated chromosome
is in the hemisphere in which the centriole was located
before it divided into two. Once again, further research
is needed to fully establish this observation.
In a total count of 916 cells, only 89 were found to
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 1 be in the metaphase stage. This indicates that the meta-
phase is rather short-lived (Graph I, table II).
D. Anaphase I
The chromosomes begin to move toward the two poles.
The two blocks of autosomes move almost parallel to one
another. It is interesting to note that while the autosomes
move together, the sex-chromosomes lag behind. Although
they start moving immediately after the initiation of the
anaphase, many cells clearly show the lagging movement
of the sex-chromosome, where the X-and the Y-chromosomes
are still closer to the equatorial plate, while the auto
somes have already moved toward the two poles (plate XVI,
figure 36) . Anaphase is a reductional phase for all the
chromosomes. Out of 901 cells counted, 98 cells were
found to be in anaphase I. (Graph I, table II) indicated
that the time lapsed for anaphase I is about the same as
that for metaphase I.
E. Telophase I
The movement of the chromosomes towards the poles is
relatively uneventful. As the two sets of autosomes reach
the poles more or less at the same time, the sex-chromosomes
lag just a bit behind (plate XVI, figure 37).
Interestingly, the spindle fibers do not begin to
elongate until almost after the chromosomes have reached
the two poles (plate XVI, figure 37 and plate XVII, figure
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 2
38). Even then, the spindle fibers are densely stained as
shown in the figures indicated above. Further work is
needed to determine if the dark stain is due to chromatin
material that may have remained attached to the spindle
fibers. However, the elongation of the spindle fibers
is a very gradual process. In a count of 922 cells, 98
cells were found in the telophase stage. (Graph I, table II).
Once the chromosomes have reached the poles, the
diffusion process begins for the chromosomes (plate XVII,
figure 39). The chromosomes condense into a mass which
then begins to diffuse, perhaps by hydration. At this time,
a nuclear membrane begins to appear at each pole. However,
one of the most interesting observations in this species
is that, upon the reaching of the chromosomes at the poles,
the cleavage or cytokinesis begins at one side of the cell,
at right angles to the longitudinal axis of the spindle
fiber (plate XVII, figure 39).
F. Cleavage or cytokinesis I
Cytokinesis in Nezara sp. represents the most inter
esting observation of cytokinesis described in literature
to date. After the chromosomes have reached the poles, a
groove appears at one end of the cell (plate XVIII, figure
40; plate XVIII, figure 41; and plate XIX, figures 42 and
43). As this groove begins to deepen, a particulate
material begins to be deposited at the equatorial plate,
(plate XVIII, figures 40 and 41; plate XIX, figures 42 and
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 3
and 43). This is reminiscent of the plants. As the groove
deepens from one end toward the other, the equatorial
plate thickens. The groove eventually meets the equatorial
plate which then progresses toward the end along with
the groove. Thus, the cytokinesis is completed. Out of
the total of 918 cells counted, 106 were in the cytokinesis
stage. (Graph I, table II).
TABLE II
Stages Number of dumber of cells Percentage cells counted at each stage
Interphase 920 302 32. 83
Prophase I 904 273 30.20
Metaphase I 916 89 9.22
Anaphase I 901 76 8.43
Telophase I 922 98 10.63
Cytokinesis 918 106 11.55
II. Equational phase
A. Resting stage II
At the end of meiosis I, there is a definite inter
phase II, (plate XX, figure 44). In interphase II, the
cell is relatively small, with an average size of 8.6 mic
rons. The cytoplasmic mass around the nucleus is relative
ly great. The nucleolus is more diffused and centrally
located.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 4
B. Prophase II
Prophase II is distinct and relatively prolonged
(plate XXII, figure 45). The nucleus is relatively dark
staining and the chromatin material is uniformily spread
(plate XXI, figure 46).
C. Metaphase II
The metaphase II is normal in that the chromosomes
line up at the equator with the sex-chromosome in the mid
dle of the ring, as is the case in metaphase I.
D. Anaphase II
The chromosomes move toward each pole, and it is
equational for all of the chromosomes, including the sex-
chromosomes (plate XXI, figure 47).
E. Telophase II
After the chromosomes have reached the poles, the
spindle fibers elongate, persisting for a while (plate XX,
figure 49) .
F. Cytokinesis II
It is interesting that the pattern of cytokinesis
is exactly the same as it was in the case of cytokinesis
I. The cell develops a cleavage at one end which progresses
toward the other end as described earlier (plate XX, fig
ures 48 and 49). However, there is no equatorial plate
that is so prominently visible in cleavage I.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 5
As a result of the completion of meiosis II, there are four spermatids which then gradually transform into sperms (plate XXIII, figure 50).
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. DISCUSSION
Chromosome Behavior
The present study was prompted by the work of Sud
(1955) who, in Dysdercus cingulatus, found that there is
no meiosis II for the sex-chromosomes. The genus Dysder
cus is extremely common not only in Asia, but also in the
Middle East, including North Africa. It seemed, therefore,
that if it is found there, the genus Dysdercus in Libya
may also reveal an abnormal behavior of the chromosomes.
Dysdercus could not be found in Libya, inspite of repeated
attempts, and it was not possible to go to Egypt for a
collection trip. It is intended, however, that the chrom
osome behavior of the genus Dysdercus found in Egypt, or
possibly Libya, will be studied at a later date.
In the meantime, the present study concentrated on
Nezara sp. which is common in Libya. Most of the collect
ion was done in the summer of 1976, with a supplementary
collection in the summer of 1977. The insects studied
were collected from Tagura, twenty miles northeast of
Tripoli.
This species has fourteen chromosomes, with the
mechanism 12 + XY. The X-chromosome is larger than the
Y-chromosome. The homologous pairing of the sex-chromo-
some is interesting in that, at the metaphase I equator-
46
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 4 7
ial plate, these chromosomes are paired along the longit
udinal axis of the spindle body. This arrangement makes
the Y-chromosome obscure from view, lying either on top of
or below the X-chromosome. In most of the other insects,
they are placed along a plane perpendicular to the long
axis of the spindle body.
The arrangement of the autosomes at the equator of
the spindle is also interesting in that the distribution
of the chromosome around the ring is not even. Instead,
five bivalents are closer to one another, whereas the
sixth bivalent is placed in a rather open space.
Finally, the cytokinesis in this species is of
great interest as it presents a unique method of division
of the dividing cell into two daughter cells.
The interest in chromosome behavior began early,
even before the turn of the century. During that time,
the chromosomes were studied in terms of their cytology
and it was only later that the relationship of the chrom
osomes to genetics was established. Although the laws
of genetics were studied by Mendel in 1865, it was not
until 1900 when Tschermak' , Correns, and De Vries indep
endently rediscovered the Mendelian laws of heredity.
Rapidly thereafter, the relationship of the chromosomes
to heredity was established, particularly in the animals.
A brief description of the chromosome behavior
in the animal kingdom is given under previous literature,
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. with a much detailed description to be found in appendix I
As indicated earlier, it was Me Clung (1901, 1902), who,
for the first time, made a distinction between the auto-
somes and the sex-chromosomes. The work of E. B. Wilson,
spanning over a period of twenty years, constituted the
most classical study of the chromosome behavior. Wilson,
working on Nezara hilaris (1905) and Nezara hilaris and
Nezara virdula (1911), found that these species possessed
a chromosome mechanism which consisted of autosomes and
sex-chromosomes of the XY type. In his studies, he found
that, almost universally, the homologous pairing of the
sex-chromosomes, X and Y, is in a different plane than
the autosomes. The autosomes pair in a plane along the
longitudinal axis of the spindle fibers. It is, therefore
that at metaphase I, one could see a ring of chromosomes
consisting of half the number of autosomes, and X and Y
in the middle.
This kind of arrangement has also been confirmed
by Asana and Makino (19 34) in Labidura riparia, which have
the X- Y-type of sex-chromosomes. Schrader (1941), work
ing on eleven species of Edessa, also confirmed a similar
arrangement with the exception that he found heteropyc-
nosis to extend beyond the normal for the sex-chromosomes
of Pentatomidae.
Manna (1951), in a compendium of his work on fourty-
three species of Hemiptera-Heteroptera, described that the
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. chromosome behavior in these insects is rather orthodox
as described earlier by Wilson. He found that, at the
diakinesis stage, the chiasmata are mostly terminal.
However, he was the first to state that the arrangement
of the chromosomes at the metaphase plate of the first
division and the second division varies from species to
species. He further described that the behavior of the
nucleus during the meiosis also varies from species to
species.
Sud (1955, 1956,1957) working on three species of
Hemiptera, Dysdercus cingulatus, Lygaeus militaris, and
Lygaeus fimbriatus, describes the chromosome behavior in
full detail. In carefully examining his diagrams, one
notices that the ring of chromosomes formed at the metaphase
I plate has autosomes placed evenly. The sex-chromosomes
(X-Y type) are in the middle, and their homologous pairing
is in a plane perpendicular to the longitudinal axis of
the spindle fibers. Thus, at the equatorial plate, one
finds a haploid number of autosomes arranged in the form
of a ring, with X and Y clearly in the middle.
In the present study, the Nezara species collected
from Libya shows that the autosomes are placed in a non
orthodox manner at the equatorial plate. The ring formed
by the autosomes consists of six chromosomes, which are
actually twelve autosomes. Five of the bivalents are
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 50 are placed evenly apart and closer together, while the
sixth bivalent is rather isolated, equidistant from its
two neighboring autosomes. In the center, only one sex-
chromosome can be seen, because the bivalent formed by
the X and the Y is in the plane of the longitudinal axis
of the spindle fibers. Thus, the metaphase I plate, in a
polar view, reveals only the haploid number of chromosomes,
as opposed to the haploid plus 1 number described for
hundreds of other species described by other investigators.
Obviously, more research is needed to determine
whether or not it is the same chromosome which is in the
looser arrangement than the other five bivalents. In
examining the slides of the serial sections prepared for
light microscopy, it seems that it is always the same
chromosome which is in this odd position. If this finding
is confirmed, through further work involving autoradio
graphy and labeling of the chromosome, it may have an
interesting relationship to its behavior. Work is planned
to determine the exact behavior of this chromosome.
In the study of the serial section, the centriole
was used'las a reference point to determine whether or not
it is the same chromosome which is placed in the "open
end" of the ring. It is evident that the "open end" is the
hemisphere where the centriole was located. Otherwise, the
behavior of this particular chromosome in terms of its ar
rangement at the equatorial plate or its migration toward
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 51 the pole is normal.
The arrangement of the sex-chromosomes in the middle
of the ring, wherein only one chromosome is seen, is rem
iniscent of the autosomes. This homologous pairing is
relatively unique as far as the previous literature is
concerned. Further, the movement of the sex-chromosomes
is in concert with that of the autosomes, without a signi
ficant difference at the anaphase stage. However, the sex-
chromosomes lag behind the autosomes, during anaphase I.
Therefore, by the time the autosomes have reached the poles,
the sex-chromosomes are slightly behind. This has been
found by several invistigators (Wilson, Sud, Hughes and
Schrader, and Manna and Chaudhry).
Cytokinesis
In the present study, a rather unique mechanism of
cytokinesis was found. At the end of telophase, the cell
begins to cleave, or furrow, on one side, which is usually
at right angles to the longitudinal axis of the spindle
fibers. The cleavage proceeds toward the middle of the
cell, while there is a definite deposit of a cytokinesis
plate at the middle of the spindle body. A total number
of 710 cells were examined and not a single cell showed
that the furrowing starts at the entire circumference of
the cell. Instead, in all of these cells the furrowing
begins on one side as described above.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 52 The matter of cleavage, or cytokinesis as it has
come to be called in recent years, has been of great inter
est to many cell biologists. Working on Cerebratulus egg
fragments, Yatsu (1908) found that furrowing in an enucleat
ed cell cuts across the spindle at the anaphase. Since
then, it has been established that cytokinesis in animals
proceeds by a process of furrowing, while in the plant cells
a plate develops in the spindle area, progressing outwards.
In the animals, however, the furrowing originates as an
indentation around the circumference of the cell, gradually
moving inward to cleave the cell into two daughter halves.
The two daughter cells are usually equal in size, as is
true for most of the cells in the plants, but the furrow
ing may be so that the two daughter cells are unequal in
size, e. g., neuroblast cells of the grasshopper embryo.
The process of furrowing or cleaving is variable, depending
upon whether the dividing cell is isolated from the others
or remains in contact with the adjacent cells. Basing his
judgment upon this observation, Gray (1931) made a distinc
tion between disjunctive and astral cleavage.
Disjunctive cleavage occurs in isolated cells such as
leucocytes, or in cells in tissue culture. No appreciable
change occurs in the shape of the dividing cells until ana
phase, when the cell elongates along the mitotic axis, and
there is an active "bubbling" of the cytoplasm of the polar
region. The bubbling consists of the repeated projection
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 53
and withdrawal of protoplasmic blisters. The two daughter
cells then proceed to move away from each other, leaving
five hyaline strands of cytoplasm between them.
Astral cleavage is characteristic of marine invert
ebrate eggs, the spherical cell dividing to give two equal
blastomores. Such eggs possess a cortical layer, the hyalo
plasm, which surrounds them peripherally. Evidence indi
cates that a flowing of the hyaloplasm into the area of
cleavage at the time of cell elongation plays a role in
the cytokinetic process. Immersion in water that is cal
cium-free or contains ether will alter, respectively, the
behavior of the hyaloplasm or the asters to the point where
cell division is altered or prevented.
Chambers and Kopac (1937) working on Echinoderm eggs,
found that the eggs halved by cleaving or furrowing,
which completely displaces the mitotic apparatus at the
equatorial plate.
Mitchison (1952) stated that cleavage actually in
volves two successive processes. First, the preliminary
contraction occurs at the cell surface in the equatorial
region. Second, there is an active and sustained suspen
sion of the membrane growing out enabling the furrow to
push inward to its completion.
Apparently, it is necessary to postulate that the
preliminary contraction phase accounts for the initiation
for furrowing. But this theory places main emphasis on
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 54
the expansion phase as the active process which develops
the energy expended in furrowing.
While these theories were being developed to under
stand the nature and dynamics of cleavage, a great deal
of experimental work had to be done. Hiramoto (1956)
aspirated the entire mitotic apparatus of an echinoderm
egg at the anaphase stage without preventing cytokinesis.
He further found, in his later research (1964-1965) , that
cleavage can continue toward its completion in sea urchin
eggs even if a portion of the mitotic apparatus is occup
ied by aqueous material. His theory seems to be that the
initiation of cleavage is laid down at the beginning of
prophase or perhaps as late as metaphase.
Rappaport (1961) working on echinoderm eggs, found
that when a spherical egg is converted to a torus, first
cleavage results in a horseshoe-shaped binucleate cell, in
which nuclei are located at the end of the horse-shoe.
Wolpert (1960) confirmed the work of Rappaport. He
went on to state that the horseshoe bends asters without
an interveining spindle and chromosomes. He concluded,
therefore, that the furrow formation does not require a
spindle or chromosomes in the division plane. Further,
furrows arise normally between the equatorial aspects of
the astral rays and develop between the two polar regions.
Of course, they can develop within two subpolar regions and
in any combinations thereof.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 55
In the present study, the cytokinesis was found to
occur through furrowing, but the mechanism for the origin
of furrowing was of interest. The furrow, or the groove,
does not start along the entire circumference of the cell.
Instead, it begins at one side of the cell which is at
right angles to the longitudinal axis of the spindle fibers.
It is almost like a notch. This furrow gradually proceeds
toward the other side. At the same time, there are spec
ific, heavily stained granules deposited at the equatorial
plate of the spindle body. As the furrow reaches this
plate, it is drawn toward the other side, behind the plate.
In other words, the plate makes first contact with that
side of the cell which is opposite to where the furrow
began. Thus, even in completing the division of the cell
into two daughter cells, there is never a trace of furrow
ing or grooving at the other side of the cell.
There are several questions that are posed:
1. Why does the furrowing begin at a specific end?
2. What prevents the furrowing from starting at the
other side?
3. What is the relationship of the furrowing to the
equatorial plate deposit?
4. Does the equatorial plate deposit enhance the
development of the furrow?
These and several other questions, are of great int-
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. erest. However, much more research work is needed to
understand the nature and mechanism of this cytokinesis.
A thorough ultrastructure study, with the aid of an
electron microscope, Elmaskop IA, was undertaken to deter
mine the nature of the furrowing, and also to understand
the reasons for the furrowing to start at one side. How
ever, the data are inconclusive at this time.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. SUMMARY
The present study describes the chromosome behavior
of two Hemipteran species, Nezara sp. and Lygaeus sp.
However, it mostly concentrates on Nezara sp.
It establishes the number of chromosomes at fourteen,
with XY type of sex-chromosome mechanism.
The chromosome behavior is normal except the follow
ing observations:
1. At the equatorial plate at metaphase I, the five
bivalents are placed close together, while the sixth
one is in the open end of the loop, equidistant from
its neighboring autosomes.
2. The sex-chromosomes move slower than the auto
somes at the anaphase stage, thus lagging a bit
behind.
3. Cytokinesis is achieved by a furrow beginning
at one end of the cell, which is at right angles to
the longitudinal axis of the spindle fibers. It
progresses toward the other end, and meets with an
equatorial plate of heavily stained granules. Both
of them continue to move until the cell is divided
into two.
57
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
tn oo
reductionally in the second. X and Y divide equationally in the first division and Y is larger than X. X-bearing class of sperms were male producing. Chromatin nucleoli. Special chromosomes. X and Y chromosomes and their distribution to the speim Y-chromosome is a little Theshorter X and thanY areX-chromosome. different XYin showedsize. marked heteropycnosis. nuclei was worked out. XY pair of thepair. male is replaced in the Chromatinfemale by nucleolian XX are not quite equal in size. Special Features At the metaphase II the X overlaps the Y chromosome. X is a sex-determiner. A peculiar chromatin element. Odd chromosomes. Accessory chromosomedivision, divides but fails equationally to divide in in thethe firstsecond. XY-XX XO XO XO XO XO XY XY-XX Appendix I Sex-chromosomes Special chromosomes. chromosomes Accessory
L. L. turcicus Lygaeus bicurcis, XY Acholla multispinosa Nezara virdula, N. hilaris XY XY Coleoptera Gelastoeoris peculation, XY XY Protenor sp. XO multespinosa, Aribus cristatus Sinea diacma, Acholla Dermatobia hominis XY Podius sp., Euschistus sp. Eyromastes marginalis Lygaeus sp., Coenus sp., Tenebrio sp. Hemiptera Protenor sp. Nezara hilaris Phasmids, OrphaniaDixippus sp., sp. Locustidae, Xiphidium fasciatum Pyrrhocoris sp. tristisflnasa Species
1912 1910 1911 1909 1909 1905 1906 1908 1898, 1901 1901, 1902 1904, 1909 1905 1899 1901 1901 1891 1899 Year
Payne Payne Stevens Stevens Wilson Wilson Montgomery Stevens and Wilson Gross Me Clung Henking Paulmier Wilson Me Clung Montgomery Montgomery SiAety Author
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
vo
an X-chromosome and a bipartite Y. In N. indica XYsome complexis composite is present as centralin which dense X chromomass and two lateral, clump of chromosomes. These chromosomes break into six to eight bodies. chromosome are both female producing. X-complex is made up of threeHe uses large the chromosomes.term idio-chromosome for an irregular XY forms an irregular knotted ring which resolves into five components rileyi.in S^. and the fifth, Y. an idio-chromosome. first division, one part is going to one pole and the threads. in the males. attachment. ceptional. other dyad going to the other pole. He suggests In the thatsecond the pycnosis of the X-chromosome X-chromosome is constructed by three parts. In the division, both parts divide. Y has a sub-terminal attachment while TheX has largea terminal end of the idiochromosome and the accessory the absence of an homologous mate for this chromosome during the growth period of the spermatocyte is due to d . 1
XY XY XY XY Y is slightly larger than x, but An unequal these arepairvery exof chromosomes. This pairconsidered XX XO, XY XY X consists of three components in Sinea diadema and Sex-chromosome is a pentoid type with fourX elements XO XY XY Appendix I Cont Idio—chromosome X-complex Sex-chromosomes Special Features
indica irrorata shooterii glauca Lepisma domestica Opossum sp. N. N. Blaps s p . Dissostexra Carolina N. N. Drosophila melanogaster Gryllotalpa borealis Notonecta undulata Locusta viridissima Arphia simplex 1923 1920 1921 1916 1916 1916 1912 1912 1913 Sinea diadema, S. rileyi 1913 Pnisontis modesta Drosophila melanogaster Brachystola magana 1912 1914, 1916 Gryllotalpa vulgaris Year Species Painter Charlton Nonidez Payne Payne Browne Payne Bridges Carothers Voinov Bridges Mohr Author
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Special Features Sex-chromosome can not be distinguished during the spermatogonial mitosis. is more nearly in step with the process of euchromo- somes than during the spermatocyte stages. "X" lies outside the autosomal ring in the metaphase. An accessory chromosome during spermatogonial division the nuclear reorganization at interkinesis. The X components become attached to each other during the early Leptotene stage, X-chromosome or in diakinesis. in the spermatogonia which fails to "touch and go" pairing system. X and Y fuse to form a heteropycnotic body either in divide in the primary spermatocyte division. XY are fused and remain so up to metaphase I. XX type in the female. XO type XY in fusedthe male.with a pair of In autosomes.male, In the first division,reductionally the sex-chromosomesand equationally dividein the second. The somes. This association forms an atelomitic chromosome. nature. The accessory chromosome is extremely diffused in The sex-chromosomes are associated withPrior the toauto second division, X and Y undergo a special type of "touch and go" pairing. XY 2 2 XX XO XY-XX XY XY XO-XX XY-XX XY-XX XY-XX XY-XX Appendix I Cont'd. Sex-chromosomes accessory chromosomes accessory chromosome
Forficula auricularis Coreids sp. Labia minor Species Phanaeus sp. Mecostethes sp. Rhytidolomia sinilis Anisolabis annulipes, Brachus quadrimaculatus Leptysma sp. Lebidura bidens, A. A. Nala lividipes marltima, Lethocerus sp. Labidura riparia. L. Labia Minor, XY bidens, Nala lividips Philocleon anomalus Scyllina cyanipes Edessa irrorata
1933 1928 1928 1927 1928 1934 1932 1940 1925 1940 1940 1941 Year 1941, 1949 Forficula auricularia
and Makino and Bacern Brauer Chickering Morgan Schrader Morgan Me Clung Hayden Helwig Long As ana As Wilson Author Callan Schrader
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
o\
Special Features diakinesis. X-chromosome undergoes an extra division. X-chromosome becomes visibly double from the early The sex-chromosomes leave the plasmosomes during trend in Dermatoptera and therefore polarization is the diplotene stage. each other in early diplotene stage. X and Y chromosomesof their readilyheteropycnosis. distinguishable because Usually come in contact with The increase in chromosome numbers is the evolutionary In both the species the hexad is made up of a V-shaped chromosome with one member of an autosome pair; the means of speciation. He describes XY type of sex-chromosome mechanism. rod is free member of the autosome pair. part. The V is the product of the fusion of the X single X-chromosome and second division is equational— The first meiotic division is reductional for the phenomenon very uncommon in Heteroptera. Y is heteropycnotic and very small in size. In first meitotic division, XY-chromosomes segregate The sex-chromosomes are positively heteropycnotic during the prophase of the first meiotic division. fifty per cent of the sperms are without a sex-chromo to the opposite poles of the spindle and in the secondchromosome. meiotic division, neither X nor Y divides. some. The failure of pairing and subsequent loss of the Y- No meiosis II for the sex-chromosomes. Consequently,
XO XO XX XY XY XY XY XY XY-XX XY XY XY Appendix I Cont'd. Sex-chromosomes
elongata Species Drosophila sp. Certain Hemipteran Species Prolabia arachidis Liaveiine coccids L. L. picticornis Loxa flavicolis Oechalia patruelis Hypochlora alba Mermiria intertexta Forty-three species of Indian XO, XY Ectrichotes dispar Lygaeus hospes L. Pandurus Dysdercus koenigii In some beetle species Hemiptera-Heteroptera. Ex: Laccotrephes maculata, Ranatra L. L. fimbriatus Dysdercus cingulatus, Lygaeus militaris,
1942 1944 1945 1947 1942 Year 1950 1950 1951 1951 1951 1952 1952,1953 1955
and Schrader Darlington Hughes Author Schrader Troddsson Heizer Bauer King Manna Ray-Chaudhry Dass Manna and Manna Sud Smith
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
to on
Special Features chromosomes in the haploid set in this species. and rarely XY type. He discovered a variation of the 15th, 16th, andRhopalopyx 17th preyssleri and N = 15 + XO and 15 + XYsomes in in Phanaeus vindex was dut to an X-autosome fus- He has recorded males with N = 8 + XO and 7 + XY in The irregularityvolves of thethe sex-bivalentskaryotype Thein only.the sex-chromosomes family in in the male are overwhelmingly XO Dicranotropis hamata.He presumed that the decrease in the number of chromo Tliere Tliere is a gradual variation in the heteropycnotic Sex-chromosomes are polymorphis. He reported instances of enlarged Y-chromosomes in Sex-chromosomes are unequal. behavior of chromosomes, particularly X-chromosome. beetles. is probably the sex-chromosome.Y-chromosome is always metacentric. chromosome andin theit is middle typified of by its secondary long arm. constricticn He suggested that a chromosome larger than the others The sex-chromosomes are well differentiated and are He termed "distance sex-bivalent." heterogametic. The X-chromosome is the longest
Appendix I Cont'c Sex-chromosomes Species Dicranotropis hamata Coporis fictor Fabr. Cathars’ius molossus CatnarsTus molossus Onitis philemon 19 56 56 19 1958 Cicadellidae Euryomnatus sp.(Coleoptera) XY XO,XY 1959 1959 Rhopalopyx ^ireyssleri, Phanaeus vindex XO, XY XY 1960 Apoqonia sp. XO 19 55 55 19 Callosobruchus chinesis XO 1963 Euprepocnemis sp. XY-XX Year 1965 1970 Brentus enchoraqo L. Corprine sp. XY XY 1971, 1972 1973 beetle species Ceratitis capitata XY-XX XY-XX 1969 Lepidoptera sp. XY-XX 1971 Tortricoidea moth XY-XX
Chatterjee Halkka Joneja Virkki Takenauche Author Kacker Suomalainen Virkki Makino Manna and Soumalainen Takenouchi Virkki White
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
CTl to
gonia of Orthoptera are longitudinally plotted. in the first division, but divide eq uationally in the second division. stages. The chromosomes divide reductionally two plasmosome. Resting stage duration.is commonly of short posed between confused and diakinesis Metaphase I phaseis irregular II is whilequite Metaregular and normal. Special Features First used the word "synapsis. Very large, clearly pale plasmosome during growth period; also, he found There is a second contraction inter No intervening stage. A second contractionbivalent. has a definite
Appendix XI Standard. The telophase chromosomes of spermata- stage and beforeis a diakinesis,second contraction. there Standard. synaptic; diffuse; contractions; Resting; pro-chromosome;ling; Leptotene; unravel synaptic; post- tonema; synaptic;spireme; post-synaptic diffuse; second synizesis; eoptera they are tinctly commonly polarized; much shorter in Hemiptera or Col- Standard except that between the second contraction stage occurs. diakinesis. there is a large, clearly defined Standard except after the confused Sequence of Prophase Stages pro-chromosomes; unravelling; Lep- often elongated and more or less dis- Standard. pale plasmosome during the growth period. osomes happened before reduction. confused stage and diakinesis, a Final gonal telophase; resting; diakinesis. In Orthoptera, the prochromosomes are and often spheroidal. All stages are standard except
This is an Arbitrarily Selected Standard Sequence Orthoptera Sinea rileyi, Pnirontis t u sConorhinus , sp. Gryllotalpa borealis Standard. Coptocyclo sp. Pyrrhocoris sp. Hemiptera modesta, Pselliodes cync- Species Orthoptera, Coleoptera Hemiptera, plants. Nezara hilaris Lygaeus sp. Mammals Standard except synapsis of chrom N. vrridula 1912 1912 1912 1906 1911 1907 1912 Year Robertson 1916 Payne Payne Gross Nowlin Wilson Wilson Wilson Author Moore 1893 Winiwarter 1901
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
rf*. O'!
leus, giving the characteristic Special Features shortly after formation offormation. spireme autosomes and second is equational.guished from the sex-chromosomes. ing of threads in pachytene is not threads and disappear before spindle the first division and divide equation tene stage. clear. One or two plasmosome appear The plasmosome can easily be distin polarized "lantern" figure. First division is reductional for the The autosomes undergo reductionally during during the second. undergoes important changes reductionalduring division. In the early stages of prophase chrom somes appear as rings while in the second prophase appears as rods. A secondary mass appears on the nuc During the spermatocytes the nucleus spermatocyte prophase, the pair chrom- bodies. The Synizesisthreads undividedtakes place during next. pachy Bouquet stage is clear. Actual break atic threads are clearly attached to The prochromosomes appear as massive diffused nucleolus. In the first which the chromosomes prepare for the
cteristic polarized Leptotene fig Sequence of Prophase Stages Standard, but ofno stagesdefinite in thethesequence gonialtransition telophase from to the chara Standard. Appendix II Cont'd. Leptotene stage is formed with the stage. ures of early growth. beginning of the growth period. Standard, but no unravelling All stages are standard except the He followed the typical seriation Wilson (1912). cryptosome; diakinesis. Diatene; peritene; phanorosome; Standard. As in Winiwarter system.
Species Phanaeus sp. Mecostethus sp.Leptisma sp. Brachus quadrimaculatus of Notonecta, N. e.g., undulata7 N. irrorata, Lepisma domestica He worked on six species N. shooterii Blaps lustanica Culex pipiens Orthoptera Hayden 25 19 Author Year Brauer 28 19 Me Clung 1927 Charlton 1921 Nonidiz 1920 Me Clung 1917 Whiting 1917 , Browne , 1916
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
CTi Ui
regularly but to migratethe autosomes. late, the comparedX-shape shows At metaphaseup owing II to re the spermatogonial division. pulsion between the sisterShe chromatids.modifies cryptosmethe description stage ofof Methe Clung. ably somewhatous near euchromosomes the two homolog as they emerge from Special Features rst four species.reductionally and Autosomesin equationallythe firstdivide division in the second. is the occurance of heteropycnosos The exact time of synapsis is prob that extends beyond that which is The prochromosomes are described in fi At anaphase I the heterosomes divide Leptotene threads are orthodox. normally notedof pentatomidae,in the sex-chromosomesalso i.e.,show heteropycnosis. the autosomes the anaphisic separation. Diakinesis shows one or two chiasmata. early stages of the growth period. formed between the bivalents of all in the second, a chromatin bridge is odox. First division is normal, the but dividing chromosomes.
Standard. Sequence of Prophase Stages standard. Standard. Standard. kinesis stage, the rest are Me Clung seriation. After telophase there is inter Standard. A special feature in Edessa irrorata Appendix IX Cont'd. Standard. He describes a differential rate in Standard. He describes pale plasmosome in the Seriation same as Winiwarter's. The pachytene and diplotene are orth
(Heteroptera) ipes, A. maritima, Stauroderus scalaris Species Rhytidolomia sinilis Forficula auricularia Tipulidae Labidura bidens, Labia E. rufomarginate Edessa irrorata minor, Anisolabis annul- Acrididae E. costalis Notococcus sp. Acholla multispinosa Aribiscristatus 1931 1933 1936 1941 1928 1940 1941 1942 1945 Loxa sp.
Bauer and Schrader Schrader Carlson Corey Hughes and Schrader Wolf Morgan Schrader Author Year Troedsson 1944 Sinea diadema
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Special Features In the second division, whichto form is normal,sperms. The early prophase is not visible. only the cells with haploid sets divide Chiasma frequencyscopus is thanhigher in Psychoda.in Telmato Anaphase I with bridge were numerous. In the confused stage, the sex-chromo He described parta Leptotene is dense partstage while ofwhere thethe otherX X-complex-hexad tetrad is diffused. somes become someseparated and they from are the heteropycnoticplasmo through out the meiosis. At the diakinesis stage, chiasmata are Hemiptera-Heteroptera. diakinesis stages. mostly terminal. Meiosis shows the typical pattern of They described the diplotene and the short by two chromosomes. He found in this species 2N = 13 is The chiasma frequency in E. Roseus is higher than that of E. Alacris. otic stage observed. the pachytene is the first mei Standard Appendix II Cont'd. Sequence of Prophase Stages Standard. Standard. All stages are standard except Standard. lowed by Wilson in an orthodox He describes ravelling,prochromosomes, Leptotene, un synizesis, and diakinesis ular stages manner. in a reg He describes the seriation fol pachytene, diplotene, confused, Standard. manner. Wilson terminology is followed. Standard. Standard. Psychoda sp. Species Pericoma modesta Taxomyia taxi Psychoda alternata Psychoda sp. Family Acndidae Telmatoscopus Pericomasp. domesta Oechallia patruelis Hypochlora alba Mermiria intertexta tera-Heteroptera. Lygaeus hospes L. L. Ranatra pandurus elongata E. E. roseus 1946 1949 1947 1949 1950 1949, 1950 1950 Year 19 51 51 19 3 species 4 of Hemip- 1951 1952 Lactotrephes maculata Aiolopus sp. 1953 Nephotettix bipunctatus 1954 Euprepocnemis alacris & and Sard Sar Sard Heizer Montalenti White King Author Manna Ray-Chaudhry Dass Kurokawa Manna and Manna Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Special Features In C. deflorata the loss of chiasmata lotene and diakinesis. is frequent between diakinesis and metaphase I. of chiasmata In C. nigricornisis frequent betweenthe loss dip rest are rod shaped. first. Large ring-bivalent at diakinesis and somes during chronous,anaphase I althoughis quite insyn some cases the The separation of the homologous chromo smallest bivalents are found to separate Kinetochore plates are absent in The chromatidsduring are notdiplotene very clearstage. They found a prometaphasephenomenon called stretch the which occurred They defined a bouquet stage. The kinetic organization of meitotic The earliest stage is the pachytene chromosomes are very different. where the chromosomes become visible. before metaphase. Oncopeltus and Dysdercus species. Sequence of Prophase Stages Standard. Appendix IX Cont'd. Standard. Standard. Standard. Standard. Standard. Standard. Standard. Species Ceracris deflorata C. C. nigricornis Athysanus argentarius Aedes dorsalis Cercopidae Culiseta mornata Dysdercus sp. Anopheles Stephensi Aedis dorsalis Aedes aegyptie Aedes dorsalis Oncopeltus sp. Author- Year Manna 1954 Halkka Rishikesh 59 19 1959 and Rai and Manna Breland et.al. 1964 Bhattacharya 1970 Comings and Okada 1972 Mescher 1966 Breland et.al. 1964 Mescher et.al. 1966 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Explanation of Plate I Fig. 1. Cell in resting stage with a centrally round nucleus and clear space (CS). Fig. 2. Cell in prophase stage. The chromosomes are still surrounded by the clear space. Fig. 3. The cell shows the end of prophase, which is indicated by disappearance of the nuclear membrane. Fig. 4. The cell is in the metaphase stage. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate I Figs. 1 and 2 (X 630) Figs. 3 and 4 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Explanation of Plate II Fig. 5 Cell in the metaphase stage. The cell shows an excellent arrangement of the chromosomes in a ring of twelve autosomes, with the sex- chromosomes, X and Y, in the middle. (Y is obscured by X). Fig. 6 Cell in anaphase stage. The rod-like chromo somes are arranged parallel to the longitud inal axis of the spindle fibers. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate II Fig. 5 (X 1250) Fig. 6 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 72 Explanation of Plate III Fig. 7 Spermatogonia in telophase stage. Fig. 8 Cell at the telophase stage shows an equatorial plate (EP). Fig. 9 Cell at the cytokinesis or cleavage stage, shows an equatorial plate (EP). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate III Figs. 7 and 8 (X 6 30) Fig. 9 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 74 Explanation of Plate IV Fig. 10 Cell at cytokinesis or cleavage stage, shows nuclear membrane (NM). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate IV Fig. 10 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 76 Explanation of Plate V Fig. 11 Cell at resting primary spermatocyte stage (RPS) with scattered mass of chromatin mat erial. Fig. 12 Cell also at RPS stage with a very clear nucleus (N). Fig. 13 Cell at RPS, surrounded by a light ground substance (GS). Fig. 14 Cell at RPS with scattered heteropycnotic knobs. (HK) . Fig. 15 Cell at leptotene stage shows leptotene threads. (LT) . Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 77 Plate V Figs. 11, 12, 13 (X 630) Figs. 14, 15 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 78 Explanation of Plate VI Fig. 16 Cell at leptotene stage shows the leptotene threads increasing in density. Fig. 17 Cell at leptotene stage shows each thread has a heteropycnotic knob at its end. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 79 Plate VI Fig. 16 (X 1250) Fig. 17 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 80 Explanation of Plate VII Fig. 18 Cell at leptotene stage shows highly chromatic nucleolus (CN-|_) . Fig. 19 Cell at bouquet stage shows high polarization. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate VII Fig. 18 (X 1250) Fig. 19 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 82 Explanation of Plate VIII Fig. 20 Cell at bouquet stage with threads coiled around one another. Fig. 21 Cell is at the bouquet stage. Shows the threads begin to condense into irregular bodies and at the same time they begin to lose their polar ization towards the nucleolus. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 83 Plate VIII Fig. 20 (X 1250) Fig. 21 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 84 Explanation of Plate IX Fig. 22 Cell at zygotene stage shows heteropycnotic knob. Fig. 23 Cell at the beginning of the diakinesis stage. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 85 Plate IX Fig. 22 (X 630) Fig. 23 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 86 Explanation of Plate X Fig. 24 Cell at diakinesis stage shows two sex-chromo- somes and the nucleolus. (N-,) . Fig. 25 Cell also at diakinesis stage at which the bivalents are twisting and show the chiasma. (Ch) . Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 87 Plate X Fig. 24 (X 630) Fig. 25 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 8 8 Explanation of Plate XI Fig. 26 Cell at diplotene stage. Fig. 27 The chromosomes at this stage begin to appear as a dumb-bell-shaped structure. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate XI Fig. 26 (X 1250) Fig. 27 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 90 Explanation of Plate XII Fig. 2 8 The cell shows the tetrads or the bivalents, which are rod-shaped or X-shaped. Fig. 29 The cell at the end of the diakinesis stage. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 91 Plate XII Fig. 28 (X 1250) Fig. 29 ( 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 92 Explanation of Plate XIII Fig. 30 Metaphase I. The X-chromosome is in the middle of the autosomes (a ). Fig. 31 Six autosomes are seen forming a ring around the sex-chromosomes (x). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. poue wt pr sin fte oyih onr Frhrrpouto poiie ihu pr ission perm without prohibited reproduction Further owner. copyright the of ission perm with eproduced R . j i r f ! i. 0 X 630) (X 30 Fig. i. 1 X 630) (X 31 Fig. Plate XIII Plate 94 Explanation of Plate XIV Fig. 32 Metaphase I. A ring of five bivalents are placed close to one another while the sixth bivalent is relatively isolated. Fig. 33 The same as Figure 32 except here we show a higher magnification. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate XIV Fig. 33 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission Explanation of Plate XV Fig. 34 The chromosomes are arranged on the periphery of the spindle in the ring form; the size of the chromosomes are almost the same but the sex-chromosomes are different. Fig. 35 The final metaphase stage. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate XV Fig. 34 (X 1250) Fig. 35 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 98 Explanation of Plate XVI Fig. 36 Anaphase I. The cell is shown at a diagonal angle. The autosomes start moving to the two poles. The X-and the Y-chromosomes are still at the equatorial plate. Fig. 37 Telophase I. The chromosomes reached the two poles to enter the telophase stage. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 99 Fig. 37 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 100 Explanation of Plate XVII Fig. 38 Two daughter cells are formed. Fig. 39 The beginning of cytokinesis stage shows the cleavage or cytokinesis beginning at one side of the cell. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 101 Plate XVII Fig. 38 (X 630) Fig. 39 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 102 Explanation of Plate XVIII Pig. 40 Cytokinesis stage. After the chromosomes have reached each pole, the cleavage (CL), is shown at one end. Fig. 41 Groove (Gr) appears at one end of the cell. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate XVIII Fig. 41 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 104 Explanation of Plate XIX Fig. 42 At this stage, the groove (Gr) at one end begins to deepen. A subcellular material begins to be deposited at the equatorial plate. Fig. 43 As the groove deepens from one end to the other, the equatorial plate thickens. The groove eventually meets the equatorial plate which progresses toward the other end of the cell. Thus, the cytokinesis is completed. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate XIX Fig. 42 (X 1250) Fig. 43 (X 1250) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 106 Explanation of Plate XX Fig. 44 The cell at interphase II. The cell is relat ively small. The cytoplasmic mass around the nucleus is relatively greater. Fig. 45 The cell at prophase II. Very distinct. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 107 Plate XX Fig. 44 (X 630) Fig. 45 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 108 Explanation of Plate XXI Pig. 46 The cell is still at prophase II. The nucleus is relatively dark stained and the chromatin material (CM) is uniformly spread. Fig. 47. The cell at anaphase II. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 109 Plate XXI Fig. 47 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 110 Explanation of Plate XXII Fig. 48 The cell at the telophase II. Fig. 49 On reaching the pole, the chromosomes begin to diffuse. The nuclear membrane begins to appear. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Ill Plate XXII Fig. 48 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 112 Explanation of Plate XXIII Fig. 50 The cells show the sperm. (S). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate XXIII Fig. 50 (X 630) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission 114 Explanation of Plate XXIV : Fig. 51 Cell under electron microscope. The nucleus (N) contains a diffused and scattered mass of chromatin material. (CM) Fig. 52 Cell also under electron microscope. The nuc leus shows scattered heteropycnotic knobs. (HK) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Plate XXIV Fig. 51 (X 11440) § « s § Fig. 52 (X 11440) Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Bibliography Arnold, J.M., 1969. Cleavage Furrow Formation in Telo- lecithal Eggs (Loligo Pelii)I. Filaments in Early Furrow Formation. Jour. Cell Biol., 41: 894-904. Asana, J.J. and Makino, S., 1934. Idiochromosomes of an Earwig, Labidura riparia. Jour. Morph., 56: 361-369. Battaglia, E., 1956. A New Type of Segregation of the Sex-chromosomes in Dysdercus koenigii Fabr. (Hemip- tera-Pyrrhocoridae). A Critical Note. Cayrologia. (Ferenje), 8: 205-213. Bauer, H., 1931. Die Chromosomen Von Tipula paludosa Meig in Eibildung and Spermatogenese. Z. Zellfv 15: 138-193. , 1947. Karyologische Natizen I. Uber Generative Polyploidie bei Dermaptera. Z. Naturf., 2: 63-66. Bhattacharya, A.K. and Manna, G.K., 1970. Structure, Behavior and Material Studies of Germinal Chromosomes in Four Species of Spittle Bugs. Proc. Nat. Acad. Sci: India, 40: 129-135. Brauer, A., 1928. Spermatogenesis of Brachus quadrimacul- atus. (Coleoptera: Brachidae). Jour. Morph. , 46: 217-240. Breland, O.P., Gassner, III, G. and Rieemann, J.G., 1964. Studies of Meiosis in the Male of the Mosquito, Cul- iseta inornata. Ann. Entomal. Soc. Am., 57: 472-479. Bridges, C.B., 1913. Non-disjunction of the Sex-chromosomes of Drosophila: Jour. Exp. Zool., 15: 587-606. , 1916. Non-disjunction as a Proof of the Chromo some Theory of Heredity. Genetics,I : 1-52, 107-163. 116 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 117 Browne, E.N., 1916. A Comparative Study of the Chromosomes of Six Species of Natonecta. Jour. Morph., 27: 119-161. Callan, H.G., 1941. The Sex Determining Mechanism of the Earwig Forficula auricularia. Jour. Genet., 41: 349-374. ______, 1949. Chiasma Interference in Diploid, Tetraploid and Interchange Spermatocytes of Earwig Forficula auricularia. Jour. Genet., 49: 209-213. Carlson, J.G., 1936. The Intergeneric Homology of a Typical Euchromosome in Several Closely Related Acridinae. Jour. Morph., 59: 123-155. Carothers, E.E., 1913. The Mendelian Ratio in Relation to Certain Orthopteran Chromosomes. Jour. Morph., 24: 487-511. Chambers, R., 1938. Structure and Kinetic Aspects of Cell Division. Jour. Cell. Comp. Physiol. , 12: 149-165. Chambers, R. and Kopac, M.J., 1937. The Coalesance of Sea Urchin Eggs with Oil Drops. Carnegie Inst. Wash. , Yearb. , 36: 88-90. Charlton, H.H., 1921. The Spermatogenesis of Lepisma domestica. Journ. Morph., 35: 381-424. Chickering, A.M. and Bacern, B., 1943. Spermatogenesis in the Belostomatidae. IV. Multiple Chromosomes in Lethocrus. Pap. Mich. Acad. Sci. , 17: 529-533. Comings, D.E., Okada, T.A., 1972. Holocentric Chromosomes in Ancopeltus: Kinetochore Plates are Present in Mitosis but Absent in Meiosis. Chromosoma (Berl.), 37: 177-192. Conklin, E.G., 1902. Karyokinesis and Cytokinesis in the Maturation, Fertilization and Cleavage of Crepidula, and Other Gasteropoda: Jour. Acad. Nat. Sci. Phila delphia, Ser. II 12: 1-121. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Corey, H.J., 1933. Chromosome study in Stauroderm. (An Orthoptera). Jour. Morph., 55: 313-347. Darlington, C.D., 1942. Chromosomes Chemistry and Gene Action. Nature, 149: 66-69. Dass, C.M.S., 1951. Meiosis in Two Members of the family Nepidae (Hemiptera-Heteroptera). Caryologia, 4: 77-85. Farr, C.H., 1918. Cel1-division by Furrowing in Mangolia. Am. Jour. Bot., 5: 379-395. Fullilove, S.L. and Jacobson, A.G., 1971. Nuclear Elong ation and Cytokinesis in Drosophila montana. Develop. Biol., 28: 560-577. Goodenough, D.A., Ito, S., and Revel, J.P.,1968. Electron Microscopy of Early Cleavage Stages in Arbacia punet ui at a. - Biol. Bull., 135: 420-471. Gray, J., 1931. A Text-book of Experimental Cytology. Univ. Press., Cambridge: 516 pp. Gr£goire, V., 1910. Les Cineses de Maturation Dans les Deux Rignes. I: La- Cellule, 16: 233-297. Gross, J., 1904. Die Spermatogenese von Syromastes, marginatus L. Zool. Jahrb. Anat. und Ontog., 20: 439-498. ______, 1907. Die Spermatogenese von Pyrrhocosis apterus L. Zool. Jahrb. Anat. und Ontog., 23: 269-336. Guignard, L., 1897. Les Centres Cin£tiques Chez les V£g£taux. Ann. Sci. Nat. Bot., 8: 177-220. Halkka, 0., 19 59. Chromosome Studies on the Hemiptera, Homoptera, Auchenorrhyncha. Ann. Acad. Scient. Ser. A. IV Biologica, 43: 1-72. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 119 Hayden, M.A., 1925. Karyosphere Formation and Synopsis in the Beetle Phanaeus. Jour. Morph., 40: 261-298. Heidenhain, M., 1908. Ueber Vanadium haematoxylin, Picro- blauschwarz und Kongo-Korynth. Zeitsch. F. Wiss. Mikr., 25: 397. Heizer, P., 1950. The Chromosome Cytology of Two Species of Specific Genus Oechalia (Pentatomidae, Hemiptera- Heteroptera), Oechalia Patruelis Stal, and Oechalia pacifica Stal. Jour. Morph., 87: 179-226. Helwig, F., 1940. Multiple Chromosomes in Philoclean anomalus (Orthoptera: Acrididae). Jour. Morph., 69: 317-328. Henking, H., 1891. Uber Spermatogenese und Deren Beziehung Zur Eientwick elung bei Pyrrhocoris apterus L. Z_. Wiss. Zool. , 51: 685-736. Hiramoto, Y., 1956. Cell Division Without Mitotic Appara tus in Sea Urchin Eggs. Exp. Cell Res., 11: 6 30-6 36. , 1964. Mechanical Properties of the Starfish Oocyte During Maturation. Biol. Bull., 127, 37 3-374. , 1965. Further Studies on Cell Division Without Mitotic Apparatus in Sea Urchin Eggs. Jour. Cell Biol., 25: 161-166. Hughes and Schrader, S., 1942. The Chromosomes of Notocooccus schraderae Vays, and the Meiotic Division Figure of Male Llaveiine Coccids. Jour. Morph., 70: 261-199. Hughes—Schrader, S., and Schrader, F., 1961. The Kinata— chore of the Hemiptera. Chromosoma (Berl.), 12: 327-350. Janeja, M.G., 1960. Chromosome Number and Sex—determining Mechanism in Twentyfive species of Indian Coleoptera. Res. Bull. Panjab Univ., II: 249-251. Janssens, F.A., 1901. La Spermatogenese Chez les Tritons Par La Cellule, 19: 5-116. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 1 2 0 Kacker, R.F., 1970. Studies on Chromosomes of Indian Coleoptera, IV in Nine Species of Family Scarabeidae. Nucleus, 13: 126-131. Kessel, R.G. and Beams, H.W., 1963. Micropinocytosis and Yolk. Formation in Oocytes of the Small Milkweed Bug. Exp. Cell Res., 30: 440-443. King, R.L., 1950. Neo-Y Chromosome in Hypochlora alba and Mermiria intertexta (Orthoptera-Acrididae). Jour. Morph., 87: 227-238. Kurokawa, H., 1953. A Study of Chromosomes in Twelve Species of Hemoptera. La Kromosoma, 15: 543-546. Lewis, W.H., 1942. The Relation of Viscosity Changes of Protoplasm to Ameboid Locomotion and Cell Division. In: The Structure of Protoplasm, W. Seifriz, ed. Iowa State College Press, pp. 16 3-19 7. , 1951. Cell Division With a Special Reference to Cells in Tissue Cultures. Ann. N.Y. Acad. Sci., 51: 1287-1294. Long, M.E., 1940. Study of a Nuclear and Cytoplasmic Rel ation in Scyllina cyanipes (Orthoptera). Jour. Morph., 67: 567-607. Mahowald, A.P. ,1963. Electron Microscopy of the Formation of the Cellular Blastoderm in Drosophila melanogaster. Exp. Cell Res., 32: 457-463. Makino, S., 1956. A Review of the Chromosome Numbers in Animals. Hokryrkan, Tokyo. Manna, G.K., 1951. Study of the Chromosomes During Meiosis in Forty-three Species of Indian Heteroptera. Proc. Zool. Soc. Bengal., 4: 1-116. , 1954. A Study of Chromosomes During Meiosis in Fifteen Species of Indian Grasshoppers. Proc. Zool. Soc., 7: 39-58. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 121 Manna/ G.K. and Chatterjee, K., 1963. Polymorphic Sex- chromosomes in Euprepocnimis sp. I. The Meiosis in the XO Type Male and in Neo-X and Neo-Y type Male. Nucleus, 6: 121-134. Marsland, D.A., 1950. The Mechanisms of Cell Division; Temperature-Pressure Experiments on the Cleavage Eggs of Arbacia panctulata. Jour. Cell. Comp. Physiol., 36: 205-227. Me Clung, C.E., 1899. A Peculiar Nuclear Element in Male Reproductive Cells of Insects. Zool. Bull. , 2: 187-197. , 1901. Notes on Accessory Chromosomes. Anat. Anz. 20: 220-226. , 1902. The Accessory Chromosome Sex-determinant. Biol. Bull., 3: 43-84. , 1917. The Multiple Chromosomes of Hesperotetix and Mermiria. Jour. Morph., 29: 519-605. , 1927. Synapsis and Related Phenomena in Mecostet- hus and Leptysma (Orthoptera). Jour. Morph., 43: 181-265. Mendel, G., 1865. Gregor Johann Mendel 1822-1884. Texte und Quellen Zu Sumem Wirken und Leben Johann Ambrosius Burth/Verlog/Leipzig 1965. p. 23-62. Mescher, A.L. and Rai, R.S., 1966. Spermatogenesis in Aedes aegyptie. Mosq. News, 26: 45-51. Mitchison, J.M., 1952. Cell Membrane and Cell Division. Soc. Exp. Biol., 6: 105-127. Mohl, H.V. , 1835. Uber die Vermehrung der Pflanjen Zelle Durch Theilung: Dissert Tubinjen. Griendjuge der Anatomie and Physiologie der Vegetabilischen Zelle. Engl. Trans. Henfrey, London. Cited by Wilson. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 122 Mohr, O.L., 1914. Studein Uber die Chromatin rei Lung, etc., Bei Cocusto. Arch. Biol., 29: 581-752. , 1916. Sind die Heterochromosomen Wahre Chrososo- men: Arch. F. Zellf., 14: 151-176. Montalenti, G., 1946. Sui Chromosomi eil Numero Dei Chias mi Nella Spermatogenesi di Psychoda sp., (dipt. Prycho- didae). Rend. Accad. Nez. Lincei. Serie 8, 1: 120-122. Montgomery, T.H., 1898. Comparative Cytologival Studies With Especial Reference to the Morphology of the Nucleolus. Jour. Morph., 15: 583-643. , 1901. A study of Chromosomes of the Germ-cells of Metazoa. Trans. Am. Phil. Soc., 20: 154-236. , 1906. Chromosomes in the Spermatogenesis of the Hemiptera-heteroptera. Trans. Amer. Phil. Soc., 27: 97-173. Moore, J.E.S., 1893. Mammalian Spermatogenesis. Anat. Anz.,8: 683-388. Morgan, W.P., 1928. A Comparative Study of the Spermatogene sis of Five Species of Earwigs. Jour. Morph., 46: 241-273. Nonidez, J.F., 19 20. The Meiotic Phenomena in the Sperm atogenesis of Blaps, with Special Reference to the X- complex. Jour. Morph., 34: 69-117. Nowlin, W.N., 1906. A Study of the Spermatogenesis of the Coptocycla aurichalcea and C. guttata with Special Reference to the Problem of Sex-terermination. Jour. Exp. Zool., 3: 581-602. Painter, T.S., 1923. The Fate of the Chromatin-nucleolus in the Opossum: (In Press). Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 123 Parshad, R., 19 57. Cytological Studies in Heteroptera II. Chromosome Complement and Meiosis in the Males of Three Pyrrhocorid bugs. Cytologia (Tokyo), 22: 127-135. Paulmier, F.C., 1899. The Spermatogenesis of Anasa tristis. Jour. Morph., 15: 223-272. Payne, F., 1909. Some New Types of Chromosomes Distribut ion and Their Relation to Sex. Biol. Bull., 16: 119- 166. , 1910. The Chromosomes of Acholla multispinosa. Biol. Bull., 18: 174-179. , 1912. A Further Study of the Chromosomes of the Reduviidae. II. The Nucleolus in the Young Oocytes and the Origin of the Ova in Gelastocoris. Jour. Morph., 23:' 331-347. , 1916. A Study of the Germ Cells of Gryllotalpa borealis and Gryllotalpa vulgaris. Jour. Morph., 28: 287-328. Provost et Dumas, 1824. Nouvelle Theorie de la Generation. Ann. Sci. Nat., I: 1-10. Rappaport, R . , 1961. Experiments Concerning Cleavage stim ulus in Sand Dollar Eggs. Jour. Exp. Zool., 148: 81-89. , 1965. Geometrical Relations of the Cleavage Stimulus in Invertebrate Eggs. Jour. Theoret. Biol., 9: 51-66. , 1969. Aster-equatorial Surface Relations and Fur1 row Establishment. Jour. Exp. Zool., 171: 59-67. Ray-Chaudhry, S.P. and Manna, G.K., 1952. Chromosome Ev olution in Wild Population of Acrididae. Proc. Ind. Acad. Sci. Sect. B., 34: 55-61. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 124 Remak, R., 1850-55. Untersuchungen Uber die Entwick Lung der Wirbelthiere: Berlin. Ris, H., 1976. Chromosomes. Ciba Symposium. Rishikesh, N., 1959. Chromosome Behavior During Sperm atogenesis of Anopheles stephensi Sensu Stricto. Cytologia, 24: 447-458. Robertson, W.R.B., 1916. Taxonomic Relations Shown in the Chromosomes of Tettigidae, Locustidae and Gryllidae: Chromosomes and Variations. Jour. Morph., 27: 197-280. Ruthmann, A. and Dahlberg, R. , 1976. Pairing and Segreg ation of the Sex-chromosomes in X-^X^ -Males of Dys- dercus intermedius with a Note on tne Kinetic Organ ization of Heteropteran Chromosomes. Chromosoma, 54: 89-97. Sari, M., 1949. Sulla Spermatogenesi di Prychoda alternate. Say e di Prycoda Cinerea Banks. (Dipt. Prychodidae). Sci. Genet. (Torina), 3: 1-2. , 1950. Sui Cromosomi di Telmatoscopus albi- punctatus con alcuni dati su quelli di T. ustulatus (Diptera: Prychodidae). Caryalogia, 3: 204-210. Schechtman, A.M. 1937. Localized Cortical Growth as the Immediate Cause of Cell Division. Science, 85: 222-223. Schrader, F., 1940. The Formation of Tetrad and the Meiotic Mitosis in the Male of Rhitidolomia senilis Say (Hemi- ptera, Heteroptera). Jour. Morph., 67: 128-141. ______, 1941. Heteropycnosis and Non-homologous Assoc- Tation of Chromosomes in Edessa irrorata (Hemiptera, Heteroptera). Jour. Morph., 69: 587-604. , 1941. The Spermatogenesis of the Earwig Anisolabis maritima Bond with Reference to the Mechanism of Chrom osomal Movement. Jour. Morph., 68: 123-141. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 125 , 1945. The Cytology of Regular Heteroploidy in the Loxa (Pentatomidae-Hemiptera). Jour. Morph., 76: 157-177. Schroeder, T.E., 1968. Cytokinesis: Filaments in the Cleavage Furrow. Exp. Cell Res., 53: 272-276. , 1970. Functional and Biochemical Aspects of Contractile Ring Filaments in Hela Cells. Jour. Cell Biol., 47: 183a. Selman, G.G. and Perry, M.M., 1970. Ultrastructural Changes in the Surface Layers of the Newt's Egg in Relation to the Mechanism of its Cleavage. Jour. Cell Sci., 6: 207-227. Sharp, L.W., 1911. The Embryo Sac of Physortigia. Bot. Gaz., 52. Cited by Wilson. Sin&ty, R. de, 1901. Recherches sur La Biologie et L' anatomie des Phasmes: La Cellule, 19: 117-278. Smith, S.G., 1952. The Cytology of Sitophilus (clandra) breyzae (I.) S. granarius (I.), and some Rynnchophora (Coleoptera). Cytologia, 17: 50-70. , 1953. Chromosome Numbers of Coleoptera. Heredity, 7: 31-48. Stay, B., 1965. Protein Uptake in the Oocytes of the Cecropia moth. Jour. Cell Biol., 26: 49-62. Stevens, N.M., 1905. Studies in Spermatogenesis with Spec ial Reference to the "Accessory Chromosome." Carneg. Inst. Wash. Publ. No. 36, Washington, D.C. Cited by Wilson. , 1908. A Study of the Germ Cells of Certain Diptera with Reference to the Heterochromosomes and the Phenomena of Synapsis. Jour. Exptl. Zool., 5: 359-374. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 126 , 1909. Further Studies on Chromosomes of Coleo ptera. Jour. Exp. Zool., 6: 101-146. Strasburger, R., 1875. Zellbildung und Unterschungen uber die Uebereintim Mung. Zelltheilung: 1st and 3rd., Jena. Cited by Wilson. Sud, G.C., 1955. Chromosome Behavior During Meiosis in Dysdercys cingulatus. Caryologia, 16. , 19 56. Spermatogenesis with Special Reference to the Cytoplasmic Inclusions in Lygaeus militaris. Panjab Univ. Res. Bull. , 1957. Chromosome Behavior During Meiosis in Lygaeus militaris and L. fimbriatus. Panj ab Univ. Res. Bull. Suomalainen, E., 1969. On the Chromosome Trivalent in Some Lepidoptera Females. Chromosoma (Berl.), 28: 298-308. , 1971. Unequal Sex-chromosomes in a Moth, Lozataenia forsterana F. (Lep., Tartricidae). Hereditas, 68: 313-316. Swann, M.M., 1952. The Nucleus in Fertilization, Mitosis, and Cell Division. Symposia Soc. Exptl. Biol., 6: 89-104. Szollosi, D., 1968. A Cytoplasmic Filament Array Assoc iated with the Cleavage Furrow. Anat. Red., 160: 437 (Abstract). Takenouchi, Y., 1955. A Short Note on the Chromosomes in Three Species of the Bruchidae (Coleoptera). Jap. Jour. Genet., 30: 7-9. ______, 1958. A Further Chromosome Survey in Thirty Species of Weevils (Curculionidae, Coleoptera). Jap. Jour. Zool., 12: 139-155. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 127 Taylor, W.R., 1924. Chromosome Shape and Individuality in (Gasteria); Amer. Jour. Bot., 11: 51-59. Troedsson, P.H., 1944. The Behavior of the Compound Sex- chromosomes in the Females of Certain Hemiptera- Heteroptera. Jour. Morph., 75: 103-147. Virchow, R., 1858. Die Cellularpathologie in Uhrer Begrun- dungauf Physioloyi sche und pathologische Gewebelehre: Berlin. Cited by Wilson. Virkki, N., 19 59. Neo-X-Y Mechanism in Two Scarobaeoid Beetles, Phanaeus vindex Macl. (Scarabaeidae) and Dorcus parallelipipedus L. (Lucanidae). Hereditas, 45: 481-494. , 196 5. Chromosomes of Certain Anthribid and Mentid Beetles from El Salvador. Ann. Acad. Sci. Fenn. A IV, 83: 1-11. , 1971. Chromosome Relationships in Some North Amer ican Scarobaeoid Beetles with a Special Reference to Pleocoma and Trox. Can. Genet. Cytol., 9: 107-125. , 1972. Formation and Maintenance of the Distance Six-bivalent in Oedionychina (Coleoptera Alticidae). Hereditas (lund), 71: 259-288. Voinov, D., 1912. Da Spermatogenese Chez Gryllotalpa vulgaris, Comptes rendus des Seaneas de La Societe de Biologie., 72: 621-623. Wolpert, L., 1960. The Nucleolus and Mechanism of Cleavage. Int. Rev. Cytol., 10: 163-216. Winiwarter, H. de, 1901. Recherches Sur L'ovogenese, etc. Archives de Biologie, 17: Cited by Wilson. White, M.J., 1947. The Cytology of Cecidomyidae (Deptera) III. The Spermatogenesis of Taxomyia toxi. Jour. Morph., 80: 1-24. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 128 , 1973. Animal Cytology and Evolution, Cambridge Univ. Press, 961 pp. Whiting, P.W., 1917. The Chromosomes of the Common House Mosquito, Culex pipiens L. Jour. Morph., 28: 523-578. Whitman, C.O., 1887. The Inadequacy of the Cell-theory of Development. Jour. Morph., 8: 639-658. Wilson, E.B., 1905. The Chromosomes in Relation to the Determination of Sex in Insects. Science, 22: 500-502. , 1905. The Behavior of the Idiochromosomes in Hemiptera. Jour Exp. Zool., 2: 371-405. , 1905. I. The Paired Microchromosomes, Idio chromosomes and Heterotropic Chromosomes in Hemiptera. Jour. Exp. Zool., 2: 507-545. , 1906. The Sexual Differences of the Chromosomes in Hemiptera with some Consideration of the Deter mination and Inheritance of Sex. Jour. Exp. Zool., 3: 1-40. , 1909. Recent Researches on the Determination and Heredity of Sex. Science, 29: 53-70. , 1909. The Accessory Chromosome in Syromastes and Pyrrhocoris, with a Comparative Review of the Types of Sexual Differences of the Chromosome Groups. Jour. Exp. Zool. , 6: 69-100. , 1911. Studies on Chromosomes VII. A Review of the Chromosomes of Nezara, with some More General Consid erations. Jour. Morph., 22: 71-110. , 1912. Studies on Chromosomes VIII. Observations on the Maturation Phenomena in Certain Hemiptera and other Forms, with Consideration on Synapsis and Red uction. Jour. Exp. Zool., 13: 345-449. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 129 _, 19 32. Polyploidy and Metaphase Patterns. Jour. Morph., 53: 443-472. Wolf, E., 1941. Die Chromosomen in der Spermatogenese Einiges Namatoceren. Chromosoma, 2: 192-246. Wolpert, L., 1960. The Mechanics and Mechanism of Cleavage. Int. Rev. Cytol. 10: 163-216. Yasuzumi, G.; Tanaka, H . ; and Tezuka, 0., 1960. Spermato genesis in Animals as Revealed by Electron Microscopy. VIII. Relation Between Nutritive Cells and the Dev eloping Spermatids in a Pond Snail Cipangopaludina malleata Reeve. Jour. Biophys. Biochem. Cytol., 7: 499-504. Yatsu, N., 1908. Annat. Zool. Jap. 6 part 4, 267. Cited by Rappaport. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.