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Visualization of Neuronal Geometry in Ventral Nerve Cord Ganglia of Acheta Domesticus

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Visualization of Neuronal Geometry in Ventral Nerve Cord Ganglia of Acheta Domesticus University of the Pacific Scholarly Commons University of the Pacific Theses and Dissertations Graduate School 1976 Visualization of neuronal geometry in ventral nerve cord ganglia of Acheta domesticus Gordon William Luke University of the Pacific Follow this and additional works at: https://scholarlycommons.pacific.edu/uop_etds Part of the Biology Commons Recommended Citation Luke, Gordon William. (1976). Visualization of neuronal geometry in ventral nerve cord ganglia of Acheta domesticus. University of the Pacific, Thesis. https://scholarlycommons.pacific.edu/uop_etds/1916 This Thesis is brought to you for free and open access by the Graduate School at Scholarly Commons. It has been accepted for inclusion in University of the Pacific Theses and Dissertations by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. Visualization of Neuronal Geometry in Ventral Nerve Cord Ganglia of AQheta domesticus A Thesis Presented To The Graduate Faculty of the Department of Biological Sciencea University of the Pacific In Partial Fullfillment of the Requirements for the Degree Master of Science by Gordon William Luke ~ March 19?6 This thesis, written and submitted by GORDON WILLIAM LUKE is approved for reconnnendation to the Committee on Graduate Studies, University of the Pacific. Department Chairman or Dean: Chairman Dated._~;;~+-·_)!.....:/fA::..::..G:=..:-?-1~-e...:..lu_· ___;_l_q_7_&____ _ TABLE·OF CONTENTS - PAGE" LIST OF FIGURES •••••• , ••••••••••••• ,., •• , ••• • •,,,.,.,, •. iv INTRODUCTION, • , • , , , , , , • , , • • , , , , , , , , • , , , • , • , , , , , , , ; , , , • , • 1 -- ------------- MATERIALS AND METHODS•••••••••~••••••••••••••••••••••••• 10 RESULTS. , , , , , , , , , ••. , , • , , ••• , , , , , , , , , ·,. , , •••• , •. , •• , • • • • • • 13 DISCUSSION, ••••••••••••••••••••••••••• ,,, •••••• ,.~~··••• )6 CONCLUSIONS, ••••• I •• I ••••••••••••••••••••••••••••••••••• 40 REFERENCES ••••• I • I ••••••••••••••••••• I ••••••• I ••••.•••••• 41 iii LIST. OF FIGURES FIGURE PAGE A. Schematic diagram of a generalized ganglion ••••••••• 7 B. Schematic. diagram of a ganglion and its cellular --- ----------- -- arrangement........................................ 7 . 1. Sche.matic diagram of a dorsal view of a portion of the ventral nerve cord of· Acheta domesticus.... 9 2. Schematic diagram of the third thoracic ganglion after im1tophoresis via nerve III ( JNv3).......... 16 3. Photomicrograph of the third thoracic ganglion after iontophoresis via nerve III ( JNvJ).......... 18 4. Increased magnification of the same preparation as in f'igure 3·•••••••••••••••••••••••••••••••••s• 18 5. Schematic diagram of the thi~d thoracic gang­ lion depicting neuronal geometry obtained by iontophoresis via nerve I (JNv1)•••••••••••••••••• 20 6. Photomicrograph of a preparation o:f' nerve I ( JNv1).. 22 7. Photomicrograph depicting the neuronal geometry obtained by iontophoresis via nerve I ( JNvl)...... 22 8. Schematic diagram of the seventh abdominal gang­ lion filled via the paired. interganglionic connectives between the seventh and eighth abdominal ganglia •••••••••••••• ~•••••••••••••••••• 24 iv LIST OF FIGURES FIGURE PAGE 9. Photomicrograph of the ventral nerve cord, gang­ lia three through seven, after axona,l ionto­ phoresis via the posterior interganglionic connectives of the seventh abdominal ganglion..... 26 10. Photomicrograph depicting partial neuronal geo- metry of the seventh abdominal ganglion after iontophoresis via the posterior interganglionic connectives." e.......................... c......... .26 11. Schematic diagram of the sixth abdominal gang­ lion after axonal iontophoresis .via the inter.~~ ganglionic connectives of the seventh abdominal ganglion •••• , •••••••••••••• , •••••• , •••••••• ·.,..... 28 12. Photomicrograph of the sixth abdominal ganglion after axonal iontophoresis via the posterior intergru1glionic connectives of the seventh ab- dominal ganglion.,.o••••••••••••••••••••••••••••••• 30 1). Schematic diagram of the fifth abdominal ganglion after axonal iontophoresis via the posterior interganglionic connectives of the seventh ab- dominal ganglion.................................. 33 v .,·-- INTRODUCTION In the common field cricket, Acheta domesticus, the ven­ tral nerve cord consists of the subesophageal ganglion and -------- ----- ---- three thoracic ganglia, followed by five smaller abdominal ganglia, The subesophageal ganglion is considered to be the fusion of three ganglia that control the organs of the low­ er portion of the head, specifically the labial palps, sal­ ivary glands, and the general area of the neck (Callahan, 1971>. The first thoracic ganglion gives_ off four pairs of nerves and innervates the muscles and hypodermis of the pro­ thorax as well as the forelegs. The second thoracic ganglion ts slightly larger than the first and also has four palrs of nerves. This ganglion supplies innervation to the middle pair of legs and to the muscles and hypodermis of the mesothorax, The third thoracic ganglion is the largest in the cricket body and is heart-shaped in appearance (Fig. 1). It gives . - off four pairs of thoracic nerves and six pairs of abdominal nerves. The thoracic nerves supply the muscles and hypodermis of the metathorax. and also the large muscles of the hind jump­ ing legs (Albrecht, 1953). The abdominal nerves innervate +__ -.,. ___ -__-_- ___ ---t-h~:f!r-s-t----t-hre-e--s-e-gmen-ts-of-t-he-a-ba-om~n-.--~he-a-bEl-&m-i-na-1-i-nne-P-~-------- vation from this ganglion, Albrecht (1953) and Callahan (19?1) 2 concluded, also includes the first three abdominal ganglia, which have fused. The fourth, fifth, sixth, and seventh abdominal ~anglia give off nerves which supply abdominal segments four through seven. The eighth, or terminal ganglion of the abdomen, is slightly larger than the previous abdominal ganglia and in­ nervates the -eighth abdominal segment, the external repro­ ductive organs, and the paired cerci (Albrecht, 1953). All of the ganglia of the ventral nerve cord are joined by a pair of thick connectives -known as interganglionic connect~ ives. These interganglionic connectives consist of bundles of axons and their supporting cells (Callahan, 1971). The length of the connectives varies with the type of ganglion supplied. The abdominal ganglia connectives measure approx­ imately 2.0 - J.Omm whereas the short and thick pair between the second and the third thoracic ganglia measures approx­ imately t.Omm. Although the nerve trunks themselves are relatively easy to visualize under the dissecting microscope, individual cell bodies, axons, and dendrites remain invisible because of the translucence of the nervous tissue. One of the older tech­ niques used for observing individual neurons was the Golgi method (reduced silver) used effectively by Cajal. Although . those neurons that are stained tend to fill entirely, it is _ _. __ estimated that only 10% of the neurons are stained and the results are often of poor quality (Pitman et al., 1972). More recently, intracellular injec·tion of procion yel:j.ow dyes has been used for the definition of neural structure. The major drawbacks of this method are that fine branches of nerve pro­ cesses often remain unobservable in wh:ole mount and the ·dye --- ------- --- itself is not electron-dense so that ultrastructural study is impossible (Kravitz, 1968). Procion yellow also has inherent weakness of poor migrational properties which ne­ cessitates the use of an electrical current (electrophoresis) (Kater et al., 1973). rrhe axonal iontophoresis method of Iles and Mullaney (1971) enables cell bodies and the:i.r processes to be filled with dye by electrophoresis along the axons of a severed nerve. Pitman et a1., (1971) modified this method by sub­ stituting cobaltous chloride for procion yellow. The use of cobaltous chloride is advantageous because it fills the neurons uniformly and when precipitated with ammonium sul­ fide it forms an electron-dense compound (cobalt sulfide) within the neuron. This technique has proved useful for elec­ tron microscopy as well as for light microscopy. It has been reported (Pitman fJt al., 1972) that the chlorides of copper, iron, and nickel should also be possible to use for ionto­ phoresis~ I have further modified the axonal iontophores~s technique by not applying any form of electrical current, · thus allowing the nerve to act as a "'wick" (after Mason, University of California, Berkeley, personal communication). The present study is an attempt to show the pattern of 4 innervation, or neuronal geometry, of various nerves leading to their respective ganglia (Fig. 1) and to obtain visualization of the finest terminal branches. A description of the cellular arrangement of a segmental ganglion would be of value in bet­ ter understand~ng the results obtained when using the axonal iontophoresis· method applied to the third through seventh -------------- ventral nerve cord ganglia. A segmental ganglion of_ the thor­ ax or abdomen is usually an oval mass of nerve ti~sue, con­ t-inuous with the interganglionic connectives (Fig. ·A). Two or three principle lateral nerves extend from its sides. The ganglion is encased in a nucleated sheath, the neurilemma, which forms a continuous covering over the nerves and the connectives. The main cellular components of the ganglion, ganglion cells, are arranged peripherally, mostly in the .. lateral and dorsal parts. TJ:l.e central and ventral parts are occupied by a neuropil mass. The lateral nerves of the gang­ lion contain
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