Summary
Gap junctions have been described ultrastructurally between neurons and epitheliomuscular cells and between neurons and their processes in the hypostome peduncle and basal disc ofHydra. All gap junctions examined inHydra exhibit two apposed plasma membranes having a 2–4 nm gap continuous with the extracellular space. The gap junctions are variable in length from 0.1–1.6 μm and appear linear or V-shaped in section. Neuronal gap junctions inHydra occur infrequently as compared to chemical synapses. Electron microscopy of serial sections has demonstrated the presence of adjacent electrical and chemical synapses (neuromuscular junctions) formed by the same neuron. In addition multiple gap junctions were present between two neurons. This is the first ultrastructural demonstration of electrical synapses in the nervous system ofHydra. Such synapses occur in neurons previously characterized as sensory-motor-interneurons on the basis of their chemical synapses; these neurons appear to represent a type of stem cell characterized by having both electrical and chemical synapses.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Anderson, P. A. V. &Mackie, G. O. (1977) Electrically coupled, photosensitive neurons control swimming in jellyfish.Science 197, 186–8.
Bennett, M. V. L. (1973) Function of electronic junctions in embryonic and adult tissues.Federation Proceedings 32, 65–75.
Bennett, M. V. L. &Goodenough, D. A. (1978) Gap junctions, electrotonic coupling and intercellular communication.Neurosciences Research Program Bulletin 16, 377–486.
Berry, M. S. &Pentreath, V. W. (1979) Electrotonic coupling among postsynaptic neurons of the characterized dopamine neuron inPlanorbis.Journal of Comparative Physiology 131, 267–75.
Campbell, R. D. (1974) Cell movements inHydra.American Zoologist 14, 523–35.
Campbell, R. D., Josephson, R. K., Schwab, W. E. &Rushforth, N. B. (1976) Excitability of nerve-free hydra.Nature 263, 388–90.
Davis, L. E. (1973) Ultrastructure of neurosensory cell development. InBiology of Hydra (edited byBurnett, A. L.), pp. 271–298. New York, London: Academic Press.
Getting, P. A. &Willows, A. O. D. (1973) Burst formation in electrically coupled neurons.Brain Research 63, 424–9.
Kass-Simon, G. &Passano, L. M. (1978) A neuropharmacological analysis of the pacemakers and conducting tissues ofHydra attenuata.Journal of Comparative Physiology 128, 71–9.
Larson, W. J. (1977) Structural diversity of gap junctions. A review.Tissue and Cell 9, 373–94.
Mackie, G. O. (1965) Conduction in the nerve-free epithelia of Siphonophores.American Zoologist 5, 439–53.
Mackie, G. O. (1970) Neuroid conduction and the evolution of conducting tissues.Quarterly Review of Biology 45, 319–32.
Macklin, M. (1976) The effect of urethane onHydra.Biological Bulletin 150, 442–52.
Rushforth, N. B. (1973) Behavioral modifications in coelenterates. InInvertebrate Learning, Vol. 1Protozoans through Annelids (edited byCorning, W. C., Dyal, J. A. andWillows, A. O. D.), pp. 123–169. New York, London: Plenum.
Sato, T. (1968) A modified method for lead staining of thin sections.Journal of Electron Microscopy (Tokyo) 17, 158–9.
Singla, C. L. (1978) Fine structure of the neuromuscular system ofPolyorchis penidllatus. (Hydromedusae, Cnidaria).Cell and Tissue Research 193, 163–74.
Spencer, A. N. (1979) Neurobiology ofPolyorchis. II. Structure of effector systems.Journal of Neurobiology 10, 95–117.
Varon, S. S. &.Somjen, G. G. (1979) Neuron-glia interactions.Neurosciences Research Program Bulletin 17, 1–239.
Westfall, J. A. (1973) Ultrastructural evidence for a granule-containing sensory-motor-interneuron inHydra littoralis.Journal of Ultrastructure Research 42, 268–82.
Westfall, J. A. (1978) Gap junctions between neurons ofHydra.American Zoologist 18, 578.
Westfall, J. A. &Kinnamon, J. C. (1978) A second sensory-motor interneuron with neurosecretory granules inHydra.Journal of Neurocytology 7, 365–79.
Westfall, J. A., Yamataka, S. &Enos, P. D. (1971) Ultra structural evidence of polarized synapses in the nerve net ofHydra.Journal of Cell Biology 51, 318–23.
Wood, R. L. (1977) The cell junctions ofHydra as viewed by freeze fracture replication.Journal of Ultrastructure Research 58, 299–315.
Wood, R. L. (1979) The fine structure of the hypostome and mouth ofHydra II. Transmission electron microscopy.Cell and Tissue Research 199, 319–38.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Westfall, J.A., Kinnamon, J.C. & Sims, D.E. Neuro-epitheliomuscular cell and neuro-neuronal gap junctions inHydra . J Neurocytol 9, 725–732 (1980). https://doi.org/10.1007/BF01205015
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01205015