Summary
An examination using the electron microscope was carried out on the visceral ganglion of the marine bivalve mollusc Spisula solida. A range of fixation, block staining and section staining technique was used to study the structure of chemical synapses. Phosphotungstic acid employed as a block stain specifically stained pre- and post-synaptic structures associated with the membrane at synapses as well as one class of granular vesicle. The specialised contacts were however shown to be rare and in many parts completely absent. Many axons, containing several types of vesicle, were shown to be varicose and it is proposed that they may function in a similar way to the unspecialised varicose terminals of vertebrate autonomic neurons. The role of membrane specialisations in intercellular adhesion is discussed. This study concludes that many synapses may be morphologically unidentified using present criteria.
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References
Benedetti, E. L., Emmelot, P.: Hexagonal array of subunits in tight junctions separated from isolated rat liver plasma membranes. J. Cell Biol. 38, 15–24 (1968).
Bennett, M. R.: In: Recent developments in vertebrate smooth muscle physiology. Proc. roy. Soc. (In the press) (1972).
Birks, R. I.: Effects of stimulation on synaptic vesicles in sympathetic ganglia, as shown by fixation in the presence of Mg2+. Proc. physiol. Soc. 216, 26–28 P. (1971).
Brightman, M. W., Reese, T. S.: Junctions between intimately apposed cell membranes in the vertebrate brain. J. Cell Biol. 40, 648–667 (1969).
Burnstock, G., Iwayama, T.: Fine-structural identification of autonomic nerves and their relation to smooth muscle. Prog. Brain Res. 34, 389–404 (1971).
Cobb, J. L. S., Bennett, T.: An electron-microscope examination of the short term effects of 6-hydroxydopamine on the peripheral adrenergic nervous system. In: 6-hydroxydopamine and catecholamine neurons, p. 33–45, T. Malmfors and H. Thoenen, eds. Amsterdam-London North-Holland (1971).
Coggeshall, R. E.: A light and electron microscope study of the abdominal ganglion of Aplysia californica. J. Neurophysiol 30, 1263–1287 (1967).
Dewey, M. M., Barr, L.: A study of the structure and distribution of the nexus. J. Cell Biol. 23, 553–587 (1964).
Gerschenfeld, H. M.: Observations on the ultrastructure of synapses in some pulmonate molluscs. Z. Zellforsch. 60, 258–275 (1963).
Gorman, A. L. F., Mirolli, M.: Axonal localization of an excitatory post-synaptic potential in a molluscan neurone. J. exp. Biol. 53, 727–736 (1970).
Gray, E. G.: Fine structural characterization of different types of synapse. Progr. Brain Res. 34, 149–160 (1971).
Gray, E. G., Young, J. Z.: Electron microscopy of synaptic structure of Octopus brain. J. Cell Biol. 21, 87–103 (1964).
Horridge, G. A.: The origins of the nervous system. In: The structure and function of nervous tissue, vol. I., G. H. Bourne, eds. p. 1–29. New York-London: Academic Press 1968.
Horridge, G. A., Mackay, B.: Naked axons and symmetrical synapses in coelenterates. Quart. J. micr. Sci. 103, 531–541 (1962).
Imaizumi, M., Hama, K.: An electron microscope study on the interstitial cells of the gizzard of the lovebird (Uroloncha domestica). Z. Zellforsch. 97, 351–357 (1969).
Jones, D. G.: A further contribution to the study of the contact region of Octopus synaptosomes. Z. Zellforsch. 103, 48–60 (1970).
Kawaguti, S., Kamashima, Y., Kobashi, K.: Electron microscopy on the radial nerve of the sea-urchin. Biol. J. Okayama Univ. 11, 87–95 (1965).
Mancini, G., Frontali, T. V.: Fine structure of the mushroom body neuropile of the brain of the roach Periplaneta americana. Z. Zellforsch. 83, 334–343 (1967).
Millonig, G.: Further observations on a phosphate buffer for osmium solution in fixation. Proc. Fifth Inter. Conference on Electromicroscopy, Philadelphia. 2, 8–11 (1962).
Palade, G. E.: A study of fixation for electron microscopy. J. exp. Md. 95, 285–293 (1952).
Pentreath, V. W., Cobb, J. L. S.: Neurobiology of Echinodermata. Biol. Rev. 47, 363–392 (1972).
Revel, J. P., Karnovsky, M. J.: Hexagonal array of subunits in intercellular junctions of the mouse heart and liver. J. Cell Biol. 33, C7-C12 (1967).
Rosenbluth, J.: The visceral ganglion of Aplysia californica. Z. Zellforsch. 60, 213–236 (1963).
Smith, D. S.: Innervation of the fibrillar flight muscles of an insect Tenebrio molitor (Coleoptera). J. biophys. biochem. Cytol. 8, 447–466 (1960).
Sotelo, C.: Permanence of post-synaptic specializations in the frog sympathetic ganglion cells after denervation. Exp. Brain Res. 6, 294–305 (1968).
Taxi, J.: Contribution a l'étude des connexions des neurons moteurs du système nerveux autonome. Ann. Sci. Nat. Zool. 7, 413–660 (1965).
Westfall, J. A., Yamataka, S., Enos, P. D.: Ultrastructural evidence of polarized synapses in the nerve net of Hydra. J. Cell Biol. 51, 318–323 (1971).
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Cobb, J.L.S., Mullins, P.A. Synaptic structure in the visceral ganglion of the lamellibranch mollusc, Spisula solida . Z.Zellforsch 138, 75–83 (1973). https://doi.org/10.1007/BF00307079
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DOI: https://doi.org/10.1007/BF00307079