DOCSLIB.ORG

Efficiency of Spermatogenesis: a Comparative Approach

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Efficiency of Spermatogenesis: a Comparative Approach Animal Reproduction Science 60±61Ž. 2000 471±480 www.elsevier.comrlocateranireprosci Efficiency of spermatogenesis: a comparative approach L. Johnson a,c,), D.D. Varner b, M.E. Roberts a, T.L. Smith a, G.E. Keillor a, W.L. Scrutchfield b a Department of Veterinary Anatomy and Public Health, College of Veterinary Medicine, Texas A&M UniÕersity, College Station, TX 77843-4458, USA b Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M UniÕersity, College Station, TX 77843-4458, USA c Center for EnÕironmental and Rural Health, College of Veterinary Medicine, Texas A&M UniÕersity, College Station, TX 77843-4458, USA Abstract Efficiency of spermatogenesis is the estimated number of spermatozoa produced per day per gram of testicular parenchyma. Spermatogenesis is the process of cell division and cell differentia- tion by which spermatozoa are produced in testes. Efficiency of spermatogenesis is influenced by species differences in the numerical density of germ cell nuclei and in the life span of these cells. Activities of spermatogonia, spermatocytes, and spermatids partition spermatogenesis into three major divisionsŽ. spermatocytogenesis, meiosis, and spermiogenesis, respectively . Spermatocyto- genesis involves mitotic germ cell division to produce stem cells and primary spermatocytes. Meiosis involves duplication of chromosomes, exchange of genetic material, and two cell divisions that reduce the chromosome number and yield four spermatids. In spermiogenesis, spherical spermatids differentiate into mature spermatids which are released in the lumen of seminiferous tubules as spermatozoa. Spermatogenesis and germ cell degeneration can be quanti- fied from numbers of germ cells in various developmental steps throughout spermatogenesis. Germ cell degeneration occurs throughout spermatogenesis; however, the greatest impact occurs during spermatocytogenesis and meiosis. There are species and seasonal influences on the developmental steps in spermatogenesis at which germ cell degeneration occurs. Number of Sertoli cells, amount of smooth endoplasmic reticulum of Leydig cells, and the number of missing generations of germ cells within the spermatogenic stage of the cycle influence efficiency of spermatogenesis. Efficiency of spermatogenesis is influenced to the amount of germ cell degenera- ) Corresponding author. Tel.: q1-979-845-9279; fax: q1-979-847-8981. E-mail address: [email protected]Ž. L. Johnson . 0378-4320r00r$ - see front matter q 2000 Published by Elsevier Science B.V. All rights reserved. PII: S0378-4320Ž. 00 00108-1 472 L. Johnson et al.rAnimal Reproduction Science 60±61() 2000 471±480 tion, pubertal development, season of the year, and aging of humans and animals. q 2000 Published by Elsevier Science B.V. All rights reserved. Keywords: Spermatogenesis; Species comparisons; Germ cell degeneration 1. Introduction 1.1. Definition and background Spermatogenesis is the sum total of the events that occur within the testis that produce spermatozoaŽ. Johnson, 1991b . Spermatogenesis occurs within seminiferous tubules of the testis. It is a lengthy, chronological process by which stem cell spermatogonia divide by mitosis to maintain their own numbers and to cyclically produce primary spermatocytes that undergo meiosis to produce haploid spermatids which differentiateŽ. without further division into spermatozoa. The efficiency of spermatogenesis is the number of spermatozoa produced per gram of testicular parenchyma and is not influenced by difference in testicular size among animals. Spermatocytogenesis, meiosis, and spermiogenesis are characterized by division andror differentiation of spermatogonia, spermatocytes, and spermatids, respectively, and are three major divisions of spermatogenesisŽ. Fig. 1 . In the bull, these divisions take 21, 23, and 17 days, respectively, for a total duration of 61 daysŽ Fig. 1; Amann, 1970. During spermatocytogenesis, stem cell spermatogonia divide by mitosis to produce other stem cells that continue the lineage throughout the adult life of malesŽ Fig. 1. Stem cells give rise to spermatogonia that cyclically produce committed spermatogo- nia which proliferate andror differentiate to produce primary spermatocytes that un- dergo meiosis. Meiosis allows exchange of genetic material between homologous chromosomes of primary spermatocytes and the production of haploid spermatidsŽ Fig. 1.Ž. During spermiogenesis Fig. 1 , spermatids differentiate from cells with spherical nuclei into mature germ cells shaped like spermatozoa for that species. The flagellum is developed into a tail, and the head of the spermatozoon is composed of the compressed nucleusŽ. source of the male genome and an acrosome with its enzymes necessary to penetrate the layers of the egg. 1.2. Kinetics of spermatogenesis The spermatogenic cycleŽ. cycle of the seminiferous epithelium is superimposed on the major divisions of spermatogenesisŽ spermatocytogenesis, meiosis, and spermiogene- sis; Fig. 1. The cycle of the seminiferous epithelium is ``a series of changes in a given areaŽ. region of seminiferous epithelium between two appearances of the same develop- mental stagesŽ.Ž steps '' Leblond and Clermont, 1952 . and lasts for 13.5 days in the bull. If spermiationŽ release of spermatozoa from seminiferous epithelium and counterpart to ovulation in the female. is used as a reference point, the spermatogenic cycle would be all the events that occur between two consecutive spermiations from a given region of the tubule. L. Johnson et al.rAnimal Reproduction Science 60±61() 2000 471±480 473 Fig. 1. Drawings and classification of germ cells at different developmental steps in the three major divisions of spermatogenesisŽ. spermatocytogenesis, meiosis, and spermiogenesis combined to make the eight stages of the cycle of bull seminiferous epithelium. During the 21 days of spermatocytogenesis, A spermatogoniaŽ. A enters cyclicŽ. at 13.5-day interval activity during stage III and undergo division to produce intermediate Ž. In , BŽ. B spermatogonia, and leptotene primary spermatocytes Ž. L . During the 23 days of meiosis, leptotene primary spermatocytes differentiate through zygoteneŽ. Z , pachytene Ž. P , and diplotene Ž. D before the first meiotic division to produce secondary spermatocytesŽ. SS , and the second meiotic division to produce Sa spermatidsŽ. Sa . During the 17 days of spermiogenesis, Sa spermatids differentiate through Sb11Ž. Sb , Sb 2 Ž.Sb21122 , Sc Ž. Sc , Sd Ž. Sd , and Sd Ž. Sd steps of development before spermiation as spermatozoa. The letters indicate the developmental step, and the numbers associated with each germ cell step indicate the developmen- tal age of each cell type in the middle of each spermatogenic stage. The cycle length is 13.5 days, and the duration of spermatogenesis is 61 days in the bull. Modified from Johnson et al.Ž. 1994 . The cycle length and frequency at which spermatozoa are released both are deter- mined by the rate at which committed spermatogonia enter the process of spermatogene- sis. The cycle length and duration of spermatogenesisŽ from the production of committed spermatogonia to spermiation.Ž are species-specific Swierstra et al, 1974; Amann, 1986 . The cycle length in days for the prairie vole is 7.2, hamster 8.7, mouse 8.9, rhesus monkey 9.5, rabbit 10.7, stallion 12.2, bull 13.5, beagle dog 13.6, and man 16 Ž.Clermont, 1963; Swierstra et al, 1974; Amann, 1981, 1986 . The stage represents an association of 4±5 germ cells, each of which is in a specific, chronological, developmental step in spermatogenesis. The assignment of stages repre- sent man-made divisions of naturally cyclically occurring cellular associations. In bulls, 474 L. Johnson et al.rAnimal Reproduction Science 60±61() 2000 471±480 the cycle has been divided into eight stagesŽ.Ž Amann, 1970 or 12 stages Berndtson and Desjardins, 1974.Ž. Fourteen stages have been described in rats Clermont, 1972 , eight in the horseŽ. Swierstra et al, 1974 , and only six stages in humans Ž. Clermont, 1963 . The bullŽ.Ž Amann, 1970 and horse Swierstra et al, 1974 . , like most species, have mainly only one stage of the cycle represented in a cross-section of the seminiferous tubule. Humans have more than two stages per cross-sectionŽ. Clermont, 1963 . 1.3. Testis Quantitative approaches have been extended to calculate daily sperm production, a quantitative measure of spermatogenesis to express the total number of spermatozoa produced per day by a testis or paired testesŽ Kennelly and Foote, 1964; Amann, 1970; Johnson, 1986b. Considering the life span and theoretical yield of a specific germ cell, a daily expression of spermatozoan production can be obtained from the number of germ cells of that type in the testisŽ. Kennelly and Foote, 1964; Amann, 1970 . The life span of a germ cell is the duration of stages of the cycle in which that cell type occurs. Theoretical yields are calculated by 2 n, where n is the number of cell divisions between that cell type and spermatids. Daily sperm production per gram of testicular parenchyma is a measure of efficiency of spermatogenesis, and it is useful in species comparisonsŽ Fig. 2; Amann et al, 1976; Fig. 2. Efficiency of spermatogenesis in various species based on potential daily sperm production per gram parenchyma at different developmental steps in spermatogenesis of the rat, bull, horse, boar, and human. Potential daily sperm production per gram is calculated from numbers of B spermatogonia, pachytene primary spermatocytes, Golgi and cap phase spermatidsŽ.
Load more

Recommended publications
  • Vocabulario De Morfoloxía, Anatomía E Citoloxía Veterinaria
    Vocabulario de Morfoloxía, anatomía e citoloxía veterinaria (galego-español-inglés) Servizo de Normalización Lingüística Universidade de Santiago de Compostela COLECCIÓN VOCABULARIOS TEMÁTICOS N.º 4 SERVIZO DE NORMALIZACIÓN LINGÜÍSTICA Vocabulario de Morfoloxía, anatomía e citoloxía veterinaria (galego-español-inglés) 2008 UNIVERSIDADE DE SANTIAGO DE COMPOSTELA VOCABULARIO de morfoloxía, anatomía e citoloxía veterinaria : (galego-español- inglés) / coordinador Xusto A. Rodríguez Río, Servizo de Normalización Lingüística ; autores Matilde Lombardero Fernández ... [et al.]. – Santiago de Compostela : Universidade de Santiago de Compostela, Servizo de Publicacións e Intercambio Científico, 2008. – 369 p. ; 21 cm. – (Vocabularios temáticos ; 4). - D.L. C 2458-2008. – ISBN 978-84-9887-018-3 1.Medicina �������������������������������������������������������������������������veterinaria-Diccionarios�������������������������������������������������. 2.Galego (Lingua)-Glosarios, vocabularios, etc. políglotas. I.Lombardero Fernández, Matilde. II.Rodríguez Rio, Xusto A. coord. III. Universidade de Santiago de Compostela. Servizo de Normalización Lingüística, coord. IV.Universidade de Santiago de Compostela. Servizo de Publicacións e Intercambio Científico, ed. V.Serie. 591.4(038)=699=60=20 Coordinador Xusto A. Rodríguez Río (Área de Terminoloxía. Servizo de Normalización Lingüística. Universidade de Santiago de Compostela) Autoras/res Matilde Lombardero Fernández (doutora en Veterinaria e profesora do Departamento de Anatomía e Produción Animal.
    [Show full text]
  • Female and Male Gametogenesis 3 Nina Desai , Jennifer Ludgin , Rakesh Sharma , Raj Kumar Anirudh , and Ashok Agarwal
    Female and Male Gametogenesis 3 Nina Desai , Jennifer Ludgin , Rakesh Sharma , Raj Kumar Anirudh , and Ashok Agarwal intimately part of the endocrine responsibility of the ovary. Introduction If there are no gametes, then hormone production is drastically curtailed. Depletion of oocytes implies depletion of the major Oogenesis is an area that has long been of interest in medicine, hormones of the ovary. In the male this is not the case. as well as biology, economics, sociology, and public policy. Androgen production will proceed normally without a single Almost four centuries ago, the English physician William spermatozoa in the testes. Harvey (1578–1657) wrote ex ovo omnia —“all that is alive This chapter presents basic aspects of human ovarian comes from the egg.” follicle growth, oogenesis, and some of the regulatory mech- During a women’s reproductive life span only 300–400 of anisms involved [ 1 ] , as well as some of the basic structural the nearly 1–2 million oocytes present in her ovaries at birth morphology of the testes and the process of development to are ovulated. The process of oogenesis begins with migra- obtain mature spermatozoa. tory primordial germ cells (PGCs). It results in the produc- tion of meiotically competent oocytes containing the correct genetic material, proteins, mRNA transcripts, and organ- Structure of the Ovary elles that are necessary to create a viable embryo. This is a tightly controlled process involving not only ovarian para- The ovary, which contains the germ cells, is the main repro- crine factors but also signaling from gonadotropins secreted ductive organ in the female.
    [Show full text]
  • Assessment of the Boar Reproductive Efficiency: Physiology and Implications Avaliação Da Eficiência Reprodutiva Do Varrão: Fisiología E Implicações
    Rev Bras Reprod Anim Supl, Belo Horizonte, n.6, p.194-198, dez. 2009. Disponível em www.cbra.org.br. Assessment of the boar reproductive efficiency: physiology and implications Avaliação da eficiência reprodutiva do varrão: fisiología e implicações Sara Williams Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, Argentina E-mail: [email protected] Abstract The main objective of a boar stud is to produce a large volume of high-quality semen per boar in an efficient and safe manner. This includes: the management of the anatomy, physiology and sexual behaviourof the young boar, that influences its performance as an adult. Normal reproductive activity in boars is coordinated by the endocrine and nervous system. Abnormal activity in one or more of these areas can result in reproductive problems. For the development of the sexual behaviour is important to considerer plays and social conditions of rearing of penmates. Play in animals is common in mammals, frequent in young and is not oriented to satisfy the immediate needs and carries appreciable costs in energy, time and even physical risk. Although, play contributes to the development of several functions that take place in the adult. Sexual behavior begin as early as 1 month of age in boars; mounting activity of penmates is observed more frequently for males than females. Some authors emphasized the importance of social conditions during rearing, due to the sexual activity showed in pubertal boars. Keywords: boars, reproduction physiology, sexual behaviour. Palavras-chave: varrão, fisiologia reprodutiva, comportamento sexual. Introduction The increased use of AI has dramatically increased the number of boars needed for semen collection on a daily basis.
    [Show full text]
  • Anatomy and Physiology of Male Gametogenesis
    1 Anatomy and Physiology of Male Gametogenesis Alex Varghese, Fnu Deepinder, Angali Chandra, Ang Wen Jeat, Furquan Pathan, Ashok Agarwal ABSTRACT Basic understanding of the male reproductive system is fundamental in effective evaluation and treatment of male infertility. This chapter is a concise introduction to the male reproductive anatomy and the intricately designed process of spermatogenesis along with its hormonal control. INTRODUCTION Understanding the fundamentals of anatomy and physiology of male reproductive system is a key to effective evaluation and treatment of male infertility. It comprises of the hypothalamic-pituitary-testis axis, epididymis, vas deferens, seminal vesicles, prostate and urethra. ANATOMY OF MALE REPRODUCTIVE SYSTEM Development The male urinary and reproductive systems share a common developmental origin. The testes and extra-testicular ducts arise from three different tissues: intermediate mesoderm, mesodermal epithelium and primordial germ cells. • The intermediate mesoderm forms a urogenital ridge that gives rise to testicular stroma and the mesonephric (Wolffian) duct. • The mesodermal (coelomic) epithelium gives rise to Sertoli cells and the paramesonephric duct. • The primordial germ cells migrate from yolk sac and give rise to the spermatagonia. Sexual differentiation occurs in the seventh week of gestation in embryos carrying the Y-chromosome. 4 ANDROLOGY LABORATORY MANUAL Transcription of the SRY gene present on the Y-chromosome leads to synthesis of testis-determining factor (TDF) protein. Secretion of TDF protein stimulates the nascent Leydig cells to produce testosterone, causing development of the mesonephric duct. It also stimulates Sertoli cells to secrete Mullerian-inhibiting factor (MIF), which leads to the regression of the paramesonephric duct. This cascade of events leads to the formation of male internal genital organs.
    [Show full text]
  • Nomina Histologica Veterinaria, First Edition
    NOMINA HISTOLOGICA VETERINARIA Submitted by the International Committee on Veterinary Histological Nomenclature (ICVHN) to the World Association of Veterinary Anatomists Published on the website of the World Association of Veterinary Anatomists www.wava-amav.org 2017 CONTENTS Introduction i Principles of term construction in N.H.V. iii Cytologia – Cytology 1 Textus epithelialis – Epithelial tissue 10 Textus connectivus – Connective tissue 13 Sanguis et Lympha – Blood and Lymph 17 Textus muscularis – Muscle tissue 19 Textus nervosus – Nerve tissue 20 Splanchnologia – Viscera 23 Systema digestorium – Digestive system 24 Systema respiratorium – Respiratory system 32 Systema urinarium – Urinary system 35 Organa genitalia masculina – Male genital system 38 Organa genitalia feminina – Female genital system 42 Systema endocrinum – Endocrine system 45 Systema cardiovasculare et lymphaticum [Angiologia] – Cardiovascular and lymphatic system 47 Systema nervosum – Nervous system 52 Receptores sensorii et Organa sensuum – Sensory receptors and Sense organs 58 Integumentum – Integument 64 INTRODUCTION The preparations leading to the publication of the present first edition of the Nomina Histologica Veterinaria has a long history spanning more than 50 years. Under the auspices of the World Association of Veterinary Anatomists (W.A.V.A.), the International Committee on Veterinary Anatomical Nomenclature (I.C.V.A.N.) appointed in Giessen, 1965, a Subcommittee on Histology and Embryology which started a working relation with the Subcommittee on Histology of the former International Anatomical Nomenclature Committee. In Mexico City, 1971, this Subcommittee presented a document entitled Nomina Histologica Veterinaria: A Working Draft as a basis for the continued work of the newly-appointed Subcommittee on Histological Nomenclature. This resulted in the editing of the Nomina Histologica Veterinaria: A Working Draft II (Toulouse, 1974), followed by preparations for publication of a Nomina Histologica Veterinaria.
    [Show full text]
  • Pretest Anatomy, Histology & Cell Biology
    Anatomy, Histology, and Cell Biology PreTestTMSelf-Assessment and Review Notice Medicine is an ever-changing science. As new research and clinical experience broaden our knowledge, changes in treatment and drug therapy are required. The editors and the publisher of this work have checked with sources believed to be reli- able in their efforts to provide information that is complete and generally in accord with the standards accepted at the time of publication. However, in view of the pos- sibility of human error or changes in medical sciences, neither the editors nor the publisher nor any other party who has been involved in the preparation or publi- cation of this work warrants that the information contained herein is in every respect accurate or complete, and they are not responsible for any errors or omis- sions or for the results obtained from use of such information. Readers are encour- aged to confirm the information contained herein with other sources. For example and in particular, readers are advised to check the product information sheet included in the package of each drug they plan to administer to be certain that the information contained in this book is accurate and that changes have not been made in the recommended dose or in the contraindications for administration. This recommendation is of particular importance in connection with new or infre- quently used drugs. Anatomy, Histology, and Cell Biology PreTestTMSelf-Assessment and Review Third Edition Robert M. Klein, PhD Professor and Associate Dean Professional Development and Faculty Affairs Department of Anatomy and Cell Biology University of Kansas, School of Medicine Kansas City, Kansas George C.
    [Show full text]
  • Índice De Denominacións Españolas
    VOCABULARIO Índice de denominacións españolas 255 VOCABULARIO 256 VOCABULARIO agente tensioactivo pulmonar, 2441 A agranulocito, 32 abaxial, 3 agujero aórtico, 1317 abertura pupilar, 6 agujero de la vena cava, 1178 abierto de atrás, 4 agujero dental inferior, 1179 abierto de delante, 5 agujero magno, 1182 ablación, 1717 agujero mandibular, 1179 abomaso, 7 agujero mentoniano, 1180 acetábulo, 10 agujero obturado, 1181 ácido biliar, 11 agujero occipital, 1182 ácido desoxirribonucleico, 12 agujero oval, 1183 ácido desoxirribonucleico agujero sacro, 1184 nucleosómico, 28 agujero vertebral, 1185 ácido nucleico, 13 aire, 1560 ácido ribonucleico, 14 ala, 1 ácido ribonucleico mensajero, 167 ala de la nariz, 2 ácido ribonucleico ribosómico, 168 alantoamnios, 33 acino hepático, 15 alantoides, 34 acorne, 16 albardado, 35 acostarse, 850 albugínea, 2574 acromático, 17 aldosterona, 36 acromatina, 18 almohadilla, 38 acromion, 19 almohadilla carpiana, 39 acrosoma, 20 almohadilla córnea, 40 ACTH, 1335 almohadilla dental, 41 actina, 21 almohadilla dentaria, 41 actina F, 22 almohadilla digital, 42 actina G, 23 almohadilla metacarpiana, 43 actitud, 24 almohadilla metatarsiana, 44 acueducto cerebral, 25 almohadilla tarsiana, 45 acueducto de Silvio, 25 alocórtex, 46 acueducto mesencefálico, 25 alto de cola, 2260 adamantoblasto, 59 altura a la punta de la espalda, 56 adenohipófisis, 26 altura anterior de la espalda, 56 ADH, 1336 altura del esternón, 47 adipocito, 27 altura del pecho, 48 ADN, 12 altura del tórax, 48 ADN nucleosómico, 28 alunarado, 49 ADNn, 28
    [Show full text]
  • Histology of Male Reproductive System
    Histology of Male Reproductive System Dr. Rajesh Ranjan Assistant Professor Deptt. of Veterinary Anatomy C.V.Sc, Rewa 1 Male Reproductive System A-Testis B-Epididymis C-Ductus Deferens D-Urethra 1-Pelvic part 2-Penile part E-Penis G-Accessory Glands 1. Seminal vesicles 2-Prostate gland 3-Bulbouretheral gland/ Cowper’s gland Testis The testis remains covered by: Tunica vaginalis- The outermost covering (peritoneal covering of the testis and epididymis). It has a parietal and visceral layer. The parietal layer remains adhered to the scrotum while the visceral layer adheres to the capsule of the testis. The space between the these two layers is called the vaginal cavity. The layers consists of mesothelium lining and connective tissue that blends with the underlying connective tissue of the scrotum. Tunica albuginea: Capsule of the testis Consists of dense irregular connective tissue, predominantly collagen fibers, few elastic fibers and myofibroblast. It has vascular layer (Tunica vasculosa) that contains anatomizing branches of testicular artery and veins. The tunica albuginea gives connective tissue trabeculae called septula testis which converge towards the mediastinum testis. The septula testis divides the testicular parenchyma into number of testicular lobules. Each lobule contains 1-4 seminiferous tubules. Mediastinum testis is a connective tissue area containing the channels of rete testis, large blood and lymph vessels. In bull it occupies the central position along the longitudinal axis of the gonad. Interstitial cells (Leydig cells) The inter-tubular spaces of the testis contain loose C.T., blood and lymph vessels, fibrocytes, free mononuclear cells and interstitial cells called Leydig cells.
    [Show full text]
  • Male Reproductive Physiology
    Why gametes? Benefits and Consequences: Male reproductive physiology from the perspective of the spermatozoon Ulrik Kvist Thessaloniki, Greece 1-3 October 2009 M.D. Ph.D. ESHRE Campus Symposium Centre for Andrology and Sexual Medicine Why gametes – Mitosis = the dominating way of reproduction in the world – all single cell organisms – We are multicellular. How do we survive – short version – Outside the body we don ´t ( Cell culture – needs sterile conditions) – After death – we are invaded – Thus the living intact body survives – how? short version – You ( as all multi cellular organisms ) have your own unique immune system directed towards all but yourself (except. Autoimmune disease). – For this there is a need for you to be unique. – Mitosis gives identical individuals – Nature needed an invention to create unique individuals- MEIOISIS – MEIOSIS created unique gametes that created unique individuals surviving endless attacks from microrganisms Meiosis Sperm, egg and fusion evolved 600 million years ago Fertilization by natural course, insemination and IVF means fusion of membranes With ICSI, a new era of man-induced evolution started 1991 - selection and fusion were by-passed by the injecting embryologist Calls for controlled and traceable conditions excluding factors modulating genetics Controlled conditions? Has the injection into the oocytes of components from chicken and cow been stopped? – egg-yolk components in cryopreservation media?? – bovine serum albumin in original sperm preparation media?? The spermatozoon A messenger cell with messages Functions of the spermatozoon as a ”messenger cell ” the postman More messenger functions Message 1 The haploid intact genome An unaffected Reproductive physiology calls for healthy grand-children DNA strand breaks – A hit in a spermatozoon in the epididymis or the test tube now! May result in a grand-child with an unbalanced translocation or inversion with impaired psychomotor development and malformations The sperm can not repair DNA-strand-breaks.
    [Show full text]
  • 26 April 2010 TE Prepublication Page 1 Nomina Generalia General Terms
    26 April 2010 TE PrePublication Page 1 Nomina generalia General terms E1.0.0.0.0.0.1 Modus reproductionis Reproductive mode E1.0.0.0.0.0.2 Reproductio sexualis Sexual reproduction E1.0.0.0.0.0.3 Viviparitas Viviparity E1.0.0.0.0.0.4 Heterogamia Heterogamy E1.0.0.0.0.0.5 Endogamia Endogamy E1.0.0.0.0.0.6 Sequentia reproductionis Reproductive sequence E1.0.0.0.0.0.7 Ovulatio Ovulation E1.0.0.0.0.0.8 Erectio Erection E1.0.0.0.0.0.9 Coitus Coitus; Sexual intercourse E1.0.0.0.0.0.10 Ejaculatio1 Ejaculation E1.0.0.0.0.0.11 Emissio Emission E1.0.0.0.0.0.12 Ejaculatio vera Ejaculation proper E1.0.0.0.0.0.13 Semen Semen; Ejaculate E1.0.0.0.0.0.14 Inseminatio Insemination E1.0.0.0.0.0.15 Fertilisatio Fertilization E1.0.0.0.0.0.16 Fecundatio Fecundation; Impregnation E1.0.0.0.0.0.17 Superfecundatio Superfecundation E1.0.0.0.0.0.18 Superimpregnatio Superimpregnation E1.0.0.0.0.0.19 Superfetatio Superfetation E1.0.0.0.0.0.20 Ontogenesis Ontogeny E1.0.0.0.0.0.21 Ontogenesis praenatalis Prenatal ontogeny E1.0.0.0.0.0.22 Tempus praenatale; Tempus gestationis Prenatal period; Gestation period E1.0.0.0.0.0.23 Vita praenatalis Prenatal life E1.0.0.0.0.0.24 Vita intrauterina Intra-uterine life E1.0.0.0.0.0.25 Embryogenesis2 Embryogenesis; Embryogeny E1.0.0.0.0.0.26 Fetogenesis3 Fetogenesis E1.0.0.0.0.0.27 Tempus natale Birth period E1.0.0.0.0.0.28 Ontogenesis postnatalis Postnatal ontogeny E1.0.0.0.0.0.29 Vita postnatalis Postnatal life E1.0.1.0.0.0.1 Mensurae embryonicae et fetales4 Embryonic and fetal measurements E1.0.1.0.0.0.2 Aetas a fecundatione5 Fertilization
    [Show full text]
  • Spermatogenesis: an Overview 2 Rakesh Sharma and Ashok Agarwal
    Spermatogenesis: An Overview 2 Rakesh Sharma and Ashok Agarwal Abstract The purpose of this chapter is to provide a comprehensive overview of spermatogenesis and the various steps involved in the development of the male gamete, including cellular processes and nuclear transformations that occur during spermatogenesis, to provide a clear understanding of one of the most complex cellular metamorphosis that occurs in the human body. Spermatogenesis is a highly complex temporal event during which a relatively undifferentiated diploid cell called spermatogonium slowly evolves into a highly specialized haploid cell called spermatozoon. The goal of spermatogenesis is to produce a genetically unique male gamete that can fertilize an ovum and produce offspring. It involves a series of intricate, cellular, proliferative, and developmental phases. Spermatogenesis is initiated through the neurological axis by the hypothalamus, which releases gonadotropin-releasing hormone, which in turn signals follicle- stimulating hormone (FSH) and luteinizing hormone (LH) to be transmit- ted to the reproductive tract. LH interacts with the Leydig cells to produce testosterone, and FSH interacts with the Sertoli cells that provide support and nutrition for sperm proliferation and development. Spermatogenesis involves a series of cell phases and divisions by which the diploid spermatogonial cells develop into primary spermatocytes via mitosis. Primary spermatocytes in the basal compartment of Sertoli cells undergo meiosis to produce haploid secondary spermatocytes in the adluminal compartment of Sertoli cells in a process called spermatocyto- genesis. This process gives the cells a unique genetic identity within the A. Agarwal () Professor and Director, Center for Reproductive Medicine, Glickman Urological and Kidney Institute, OB-GYN and Women’s Health Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk A19.1, Cleveland, OH 44195, USA e-mail: [email protected] A.
    [Show full text]
  • Spermatogenesis Is the Process, in Which Spermatozoa Are Produced from Male Primordial Germ Cells by Way of Mitosis and Meiosis
    DEVELOPMENT AND MATURATION OF THE MALE GAMETES • Embryology is a science that studies the formation and development of organisms. • It examines their life before the birth of humans and animals. It also examines the hatching period of poultry. • Life begins with the union of spermatozoon and ovum. The resulting structure is called zygote. • Prenatal period is the process, in which a human or animal embryo during pregnancy, from fertilization to birth. • Postnatal period is the life of a human or an animal after birth. • The prenatal period passes through in the uterus in human and animals. The prenatal period in poultry is the incubation period in the egg. Prenatal period is divided into two parts. Embryonic period: It is the period between zygote formation and organs occurrence. The developing organism is called embryo. Fetal period: It is the period between from organs formation and until to birth. The developing organism is called fetus. • Birth occurs when the fetus matures in mammals. And begins postnatal life. • In the poultry, this period corresponds to the hatching. • The events from the zygote to the formation of the organs are examined at the general embryology. • The changes in the formation of the organs in the fetal stage are examined at the special embryology. • In order to understand the embryonic period, male and female reproductive cells must be known. • A zygote is a single cell, which has formed as the result of the merging of an egg cell and a sperm. • In the zygote contains chromosomes and genes from the mother and father. It is a single cell (unicellular) and divides into several times.
    [Show full text]