Summary
Pituicytes of Rana pipiens could be classified into two types, pale and dense, according to their relative densities of cytoplasm and the populations of free ribosomes and cell organelles. An intermediate type of pituicyte was also recognized.
Lipid droplet such as are typical in the cytoplasm of mammalian pituicytes, are not in the cytoplasm of either types of frog pituicyte. Both types have long cytoplasmic processes which run among the nerve fibers, and some of them end at the pericapillary space.
Nerve endings making synapse-like contacts with the cell bodies or the processes of the pituicyte are frequent. According to the structures and sizes of granules and vesicles in the nerve endings, these endings are classified into one of three types: 1) A, which appears to be a peptidergic neuronal ending containing dense granules 1,200–2,000 Å in diameter and small clear vesicles 300–400 Å in diameter; 2) B, which appear to be monoaminergic endings containing cored vesicles 600–1,000 Å in diameter and small clear vesicles 300–500 Å in diameter; 3) C, which appear to be cholinergic endings containing only small clear vesicles. Type C endings are relatively rare. In the synaptic area the axonal membranes appose those of the pituicytes across a gap of about 200 Å and numerous “presynaptic” vesicles are clustered or accumulated near the presynaptic membranes.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Barer, R., Lederis, K.: Ultrastructure of the rabbit neurohypophysis with special reference to the release of hormones. Z. Zellforsch. 75, 201–239 (1966).
Bargmann, W., Knoop, A.: Elektronenmikroskopische Beobachtungen an der Neurohypophyse. Z. Zellforsch. 46, 242–251 (1957).
—, Lindner, E., Andres, K. H.: Über Synapsen an endokrinen Epithelzellen und die Definition sekretorischer Neurone. Untersuchungen am Zwischenlappen der Katzenhypophyse. Z. Zellforsch. 77, 282–298 (1967).
Bern, H. A., Nishioka, R. S., Mewaldt, L. R., Farner, D. S.: Photoperiodic and osmotic influences on the ultrastructure of the hypothalamic neurosecretory system of the white-crowned sparrow, Zonotrichia leucophrys gambellli. Z. Zellforsch. 89, 198–227 (1966).
Bodian, D.: Cytological aspects of neurosecretion in opossum neurohypophysis. Bull. Johns Hopk. Hosp. 113, 57–93 (1963).
Dellman, H. D., Owsley, P. A.: Investigation on the hypothalamo-neurohypophysial neurosecretory system of the grass frog (Rana pipiens) after transection of the proximal neurohypophysis. II. Light- and electron-microscopic findings in the disconnected distal neurohypophysis with special emphasis on the pituicytes. Z. Zellforsch. 94, 325–336 (1966).
Fatehchand, R.: New Scientist 24, 726 (1964). Cit. by Knowles and Vollrath (1965).
Fujita, H., Hartmann, J. F.: Electron microscopy of neurohypophysis in normal, adrenaline-treated and pilocarpine-treated rabbits. Z. Zellforsch. 54, 734–763 (1961).
Gerschenfeld, H. M., Tramezzani, J. H., De Robertis, E.: Ultrastructure and function in neurohypophysis of the toad. Endocrinology 66, 741–762 (1960).
Hartmann, J.: Electron microscopy of the neurohypophysis in normal and histamine-treated rats. Z. Zellforsch. 48, 291–308 (1958).
Knowles, F., Vollrath, L.: Synaptic contacts between neurosecretory fibers and pituicytes in the pituitary of the eel. Nature (Lond.) 206, 1168–1169 (1965).
—: A functional relationship between neurosecretory fibers and pituicytes in the eel. Nature (Lond.) 208, 1343 (1966).
Kobayashi, H., Bern, H. A., Nishioka, R. S., Hyodo, Y.: The hypothalamo-hypophyseal neurosecretory system of the parakeet, Melopsittacus undulatus. Gen. comp. Endocr. 1, 545–564 (1961).
Kratzsch, E.: Experimentell-morphologische Untersuchungen am Zwischenhirn-Hypophysensystem der Ratte bei Polyurie infolge Alloxanvergiftung. Z. Zellforsch. 36, 371–380 (1951).
Krsulovic, J., Brückner, G.: Morphological characteristics of pituicytes in different functional stages. Light- and electronmicroscopy of the neurohypophysis of the albino rat. Z. Zellforsch. 99, 210–220 (1969).
Kurosumi, K.: Personal communication (1970).
—, Matsuzawa, T., Kobayashi, Y., Sato, S.: On the relation between the release of neurosecretory substance and lipid granules of pituicytes in the rat neurohypophysis. Gunma Symposia on Endocrinology, vol. 1, p. 87–118. Published from Institute of Endocrinology, Gunma University, Maebashi, Japan (1964).
Lederis, K.: Ultrastructural and biological evidence for the presence and likely functions of acetylcholine in the hypothalamo-neurohypophysial system. In: Neurosecretion (ed. F. Stutinsky), p. 155–164. Berlin-Heidelberg-New York: Springer 1967.
Leonhardt, H., Backhus-Roth, A.: Synapsenartige Kontakte zwischen intraventrikulären Axonendingungen und freien Oberflächen von Ependymzellen des Kaninchengehirns. Z. Zellforsch. 97, 369–376 (1969).
Luft, J. H.: Improvements in epoxy resin embedding methods. J. biophys. biochem. Cytol. 9, 409–414 (1961).
Millonig, G.: A modified procedure for lead staining of thin sections. J. biophys. biochem. Cytol. 11, 736–739 (1961).
Nakai, Y., Gorbman, A.: Evidence for a doubly innervated secretory unit in the anuran pars intermedia. II. Electron microscopic studies. Gen. comp. Endocr. 13, 108–116 (1969).
Nishioka, R. S., Bern, H. A., Mewaldt, L. R.: Ultrastructural aspects of the neurohypophysis of the white-crowned sparrow, Zonotrichia leucophrys gambelii, with special reference to the relation of neurosecretory axons to ependyma in the pars nervosa. Gen. comp. Endocr. 4, 304–313 (1964).
Oota, Y.: Fine structure of the median eminence and the pars nervosa of the mouse. J. Fac. Sci. Univ. Tokyo IV. 10, 155–168 (1963).
—, Kobayashi, H.: Fine structure of the median eminence and the pars nervosa of the bullfrog, Rana catesbeiana. Z. Zellforsch. 60, 667–687 (1963).
Palay, S. L.: An electron microscope study of the neurohypophysis in normal, hydrated, and dehydrated rats. Anat. Rec. 121, 348 (1955).
Rennels, E. G., Drager, G. A.: The relationship of pituicytes to neurosecretion. Anat. Rec. 122, 193–203 (1955).
Rodriguez, E. M., La Pointe, J.: Histology and ultrastructure of the neural lobe of the lizard, Klauberina riversiana. Z. Zellforsch. 95, 37–57 (1969).
Romeis, B.: Die Hypophyse. Innersekretorische Drüsen. II.In: Handbuch der mikroskopischen Anatomie des Menschen, Bd. VI/3, hrsg. von W. v. Möllendorff. Berlin: Springer 1940.
Roth, L. M., Luse, S. A.: Fine structure of the neurohypophysis of the opossum (Didelphis virginiana). J. Cell Biol. 20, 459–472 (1964).
Smoller, C. G.: Ultrastructural studies on the developing neurohypophysis of the pacific treefrog, Hyla regilla. Gen. comp. Endocr. 7, 44–73 (1966).
Vollrath, L.: The ultrastructure of the eel pituitary at the elver stage with special reference to its neurosecretory innervation. Z. Zellforsch. 73, 107–131 (1966).
Wingstrand, K. G.: Comparative anatomy and evolution of the hypophysis. In: The pituitary gland (G. W. Harris and B. T. Donovan, eds.), p. 58–126. London: Butterworths 1966.
Wittkowski, W.: Synaptische Strukturen und Elementargranula in der Neurohypophyse des Meerschweinchens. Z. Zellforsch. 82, 434–458 (1967).
Zambrano, D., De Robertis, E.: Ultrastructure of the peptidergic and monoaminergic neurons in the hypothalamic neurosecretory system of anuran batracians. Z. Zellforsch. 90, 230–244 (1968).
Author information
Authors and Affiliations
Additional information
The author wish to express his hearty thanks Professor Dr. A. Gorbman, Zoology Department, University of Washington, Seattle, U.S.A. and Professor Dr. H. Fujita for their helpful advices and criticisms. The frog tissues were obtained and fixed in Professor A. Gorbman's laboratory supported by U.S.P.H.S. grant NS 04887.
Rights and permissions
About this article
Cite this article
Nakai, Y. Electron microscopic observations on synapse-like contacts between pituicytes and different types of nerve fibers in the anuran pars nervosa. Z. Zellforsch. 110, 27–39 (1970). https://doi.org/10.1007/BF00343983
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF00343983