Summary
Within the medulla externa of the crayfish compound eye a class of axonal endings with similar characteristics to the photoreceptor terminals of the lamina ganglionaris were studied with light and electron microscopic techniques. These terminals are restricted to the superficial layers of the medulla externa and each is marked by a rod-shaped inclusion selectively impregnated with reduced silver methods.
Electron microscopy of the medullary terminals confirms the presence of a rod inclusion composed of fine regularly arranged filaments. These inclusions are often closely associated with mitochondria and glycogen deposits within the endings. Synaptic contacts made by these terminals are characterized by a presynaptic ribbon density which is in contact with two or three postsynaptic elements. Often one postsynaptic element participates in more than one synaptic complex. Numerous invaginated processes, microtubules, synaptic vesicles, and ER cisternae are also present in the medullary terminals.
The eighth retinula cell in the retina of the crayfish studied here resembles that previously observed by Nässel (1976). The similarity of the medullary terminals to the photoreceptor endings in the lamina suggest that they may belong to one of the eight photoreceptor cells forming an ommatidium.
Similar content being viewed by others
References
Albrecht, M.H.: Mounting frozen sections with gelatin. Stain. Technol. 29, 89–90 (1954)
Cajal, S.R., Sanchez, D.: Contribucion al conocimiento de los centros opticos. Trab. Lab. Invest. Biol. Univ. Madrid 13, 1–168 (1915)
Campos-Ortega, J.A., Strausfeld, N.J.: The columnar organization of the second synaptic region of the visual system of Musca domestica L.I. Receptor terminals in the medulla. Z. Zellforsch. 124, 561–585 (1972)
Ebbesson, S.O.E.: The selective silver-impregnation of degenerating axons and their synaptic endings in nonmammalian species. In: Contemporary research methods in neuroanatomy (WJ.H. Nauta and S.O.E. Ebbesson, eds.), pp. 132–161. Berlin-Heidelberg-New York: Springer 1970
Eguchi, E.S., Waterman, T.H.: Orthogonal microvillus pattern in the eighth rhabdomere of the rock crab Grapsus. Z. Zellforsch. 137, 145–157 (1973)
Elofsson, R., Odselius, R.: The anostracan rhabdome and the basement membrane. An ultrastructural study of the Artemia compound eye (Crustacea). Acta Zool. 56, 141–153 (1975)
Hafner, G.S.: The neural organization of the lamina ganglionaris in the crayfish: A Golgi and E.M. study. J. Comp. Neurol. 152, 255–280 (1973)
Hafner, G.S.: The ultrastructure of retinula cell endings in the compound eye of the crayfish. J. Neurocytol. 3, 295–311 (1974)
King, D.G.: Organization of crustacean neuropil. I. Patterns of synaptic connections in lobster stomatogastric ganglion. J. Neurocytol. 5, 207–237 (1976)
Kunze, P., Boschek, C.B.: Elektronenmikroskopische Untersuchung zur Form der achten Retinulazelle bei Ocypode. Z. Naturforsch. [C] 23, 568–569 (1968)
MaCagno, E.R., Levinthal, C.: Computer reconstruction of the cellular architecture of the Daphnia magna optic ganglion. In: 33rd Ann. Proc. Electron Microscopy Soc. Amer. Las Vegas, Nevada (G.W. Baily, ed.), pp. 284–285 (1975)
Meyer-Rochow, V.B.: Larval and adult eye of the western Rock lobster (Panulirus longipes). Cell Tissue Res. 162, 439–457 (1975)
Nässel, D.R.: The organization of the lamina ganglionaris of the prawn Pandalus borealis (Kröyer). Cell Tissue Res. 163, 445–464 (1975)
Nässel, D.R.: The retina and retinal projection on the lamina ganglionaris of the crayfish Pacifastacus leniusculus Dana. J. Comp. Neurol. 167, 341–360 (1976)
Nässel, D.R.: Types and arrangements of neurons in the crayfish optic lamina. Cell Tissue Res. 179, 45–75 (1977)
Ribi, W.A.: Neurons in the first synaptic region of the bee, Apis mellifera. Cell Tissue Res. 148, 227–286 (1974)
Strausfeld, N.J.: Golgi studies on insects. II. The optic lobes of diptera. Philos Trans. R. Soc. Lond. [Biol.] 258, 135–223 (1970)
Strausfeld, N.J.: The organization of the insect visual system (light microscopy). I. Projections and arrangements of neurons in the lamina ganglionaris of Diptera. Z. Zellforsch. 121, 377–441 (1971)
Strausfeld, N.J., Blest, A.D.: Golgi studies on insects. I. The optic lobes of Lepidoptera. Philos Trans. R. Soc. Lond. [Biol.] 258, 81–134 (1970)
Trujillo-Cenóz, O., Melamed, J.: Electron microscope observations on the peripheral and intermediate retinas of dipterans. In: The functional organization of the compound eye (C.G. Bernhard, ed.), pp. 339–361. Oxford: Pergamon Press 1966
Author information
Authors and Affiliations
Additional information
This work was supported in part by grants from the National Science Foundation (BNS77-15803) and National Institute of Health (NS08964)
The authors wish to acknowledge the technical assistance of Ms. Georgia Hammond-Soltis
Rights and permissions
About this article
Cite this article
Hafner, G.S., Tokarski, T.R. Evidence for putative photoreceptor axon terminals in the medulla externa of the crayfish. Cell Tissue Res. 195, 331–340 (1978). https://doi.org/10.1007/BF00236729
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00236729