Summary
The submicroscopic structure of the nerve cells in the planarian brain was studied. Close similarities with neurons of other invertebrates were noted. In the cytoplasm of the planarian nerve cells there are at least three types of vesicular inclusions: 1) Clear vesicles (200–800 Å in epon embedded tissue) similar in morphological appearance to classical synaptic vesicles. These have generally some content of extremely low density but occasionally a dense core. 2) Dense vesicles (400–1,200 Å in epon embedded tissue) containing highly osmiophilic granules. Between the limiting membrane of the vesicle and the granule there is always a clear rim of variable width. These vesicles closely resemble synaptic vesicles described in vertebrate adrenergic endings. 3) Neurosecretory vesicles (600–1,300 Å in Vestopal embedded tissue) similar to elementary granules observed in neurosecretory systems in vertebrates and invertebrates. All three vesicle types have the same mode of origin from the Golgi membranes. All are present in the nerve cell processes of the neuropil as well as in the perikarya. Any given perikaryon or axon contains only one of the three vesicle types. All of these vesicles are considered to be discharged into the axons from their site of origin within the perikaryon.
Similar content being viewed by others
References
Afzelius, B. A., and G. Fridberg: The fine structure of the caudal neurosecretory system in Raia batis. Z. Zellforsch. 59, 289–308 (1963).
Bargmann, W., u. A. Knoop: Elektronenmikroskopische Beobachtungen an der Neurohypophyse. Z. Zellforsch. 46, 242–251 (1957).
—, u. A. Thiel: Elektronenmikroskopische Studie an der Neurohypophyse von Tropidonotus natrix (mit Berücksichtigung der Pars intermedia). Z. Zellforsch. 47, 114–126 (1957).
Bern, H. A., R. S. Nishioka, and I. R. Hagadorn: Association of elementary neurosecretory granules with the Golgi complex. J. Ultrastruc. Res. 5, 311–320 (1961).
Coggeshall, R. E., and D. W. Fawcett: The fine structure of the central nervous system of the leech Hirudo medicinalis. J. Neurophysiol. 27, 229–289 (1964).
Dalton, A. G.: Morphology and physiology of the Golgi apparatus. Cell physiol. of neoplasia, p. 161–184. Austin: Univ. of Texas Press 1960.
De Robertis, E.: Submicroscopic morphology of the synapses. Int. Rev. Cytol. 8, 61–94 (1959).
—, and S. H. Bennett: Ultrastructure of earthworm and frog synapses. Fed. Proc. 13, 35 (1954).
—: Some features of the Submicroscopic morphology of synapses in frog and earthworm. J. biophys. biochem. Cytol. 1, 47–58 (1955).
—, and A. Pellegrino de Iraldi: Plurivesicular secretory processes and nerve endings in the pineal gland of the rat. J. biophys. biochem. Cytol. 10, 361–372 (1961).
Gerschenfeld, H. M.: Observations on the ultrastructure of synapses in some pulmonate molluscs. Z. Zellforsch. 60, 258–275 (1963).
Gray, E. G.: A morphological basis for presynaptic inhibition. Nature (Lond.) 193, 82 (1962).
Hagadorn, I. R., H. A. Bern, and R. S. Nishioka: The fine structure of the supraesophageal ganglion of the rhychobdellid leech, Theromyzon rude, with special reference to neurosecretion. Z. Zellforsch. 58, 714–758 (1963).
Hyman, L. H.: Nervous system of turbellaria. The invertebrates, vol. 2, pp. 83–89. New York: McGraw-Hill Book Co. 1951.
Murakami, M.: Elektronenmikroskopische Untersuchungen der neurosekretorischen Zellen im Hypothalamus der Maus. Z. Zellforsch. 56, 277–299 (1962).
Palay, S. L.: Structure and function in the neuron. In: Progress in neurobiology. I. Neurochemistry (ed. S. Korey and J. I. Nurnberger), pp. 64–82. New York: Hoeber-Harper 1956.
—: The fine structure of neurohypophysis. II. Ultrastructure and cellular chemistry of neuronal tissue (ed. S. Korey and J. I. Nurnberger), pp. 31–49. New York: Hoeber-Harper 1957.
—: The fine structure of secretory neurons in the preoptic nucleus of the gold fish (Carassius auratus). Anat. Rec. 138, 417–443 (1960).
Pedersen, K. G.: Studies on the nature of planarian connective tissue. Z. Zellforsch. 53, 569–608 (1961a).
—: Some observations on the fine structure of planarian protonephridia and gastrodermal phagocytes. Z. Zellforsch. 53, 609–628 (1961b).
Pellegrino de Iraldi, A., and E. De Robertis: Electronmicroscope study of a special neurosecretory neuron in the nerve cord of the earthworm. In: Electron microscopy. Proc. Vth Congr. Electron Microso., vol. 2, p. U-7. New York: Academic Press 1962.
Reynolds, E. S.: The use of lead citrate at high pH as an electron opaque stain in electron microscopy. J. Cell Biol. 17, 209–212 (1963).
Richardson, K. C.: The fine structure of autonomic nerve endings of the rat vas deferens. J. Anat. (Lond.) 96, 427–442 (1962).
Röhlich, P., u. L. T. Török: Elektronenmikroskopische Untersuchungen des Auges von Planarien. Z. Zellforsch. 54, 362–381 (1961).
Rosenbluth, J.: The visceral ganglion of Aplysia calfornica. Z. Zellforsch. 60, 213–236 (1963).
Sano, Y., u. A. Knoop: Elektronenmikroskopische Untersuchungen am kaudalen neurosekretorischen System von Tinca vulgaris. Z. Zellforsch. 49, 464–492 (1959).
Scharrer, E., and S. Brown: Neurosecretion. XII. The formation of neurosecretory granules in the earthworm Lumbricus terrestris L. Z. Zellforsch. 54, 530–540 (1961).
Skaer, R. J.: Some aspects of the cytology of Polycelis nigra. Quart. J. micr. Sci. 102, 295–317 (1961).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Oosaki, T., Ishii, S. Observations on the ultrastructure of nerve cells in the brain of the planarian, Dugesia gonocephala . Zeitschrift für Zellforschung 66, 782–793 (1965). https://doi.org/10.1007/BF00342956
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00342956