Summary
In the crested newt, the ultrastructural organization of the pars nervosa is analogous to that already known in non-mammal tetrapods. An orderly array of ependymal cells makes up the inner limiting layer while less abundant pituicytes are irregularly distributed within this organ. “Light” and “dark” pituicytes can be distinguished on the basis of the relative density of the cytoplasmic matrix and the distribution of the cell organelles.
Both the ependymal cells and pituicytes are rich in dense bodies and possess extensive processes which ramify among the nerve fibers, often reaching the pericapillary space which they can line for long distances.
The main components of the pars nervosa are nerve fibers and nerve terminals (type A), containing electron dense granules 1200–2000 Å in diameter together with clear vesicles averaging 250–400 Å. These fibers are likely to correspond to the aldehyde fuchsin positive neurosecretory fibers revealed by light microscopy. Differences in the granule size within the fibers and terminals lead to further recognition of two subgroups (A1 and A2).
Other fibers and terminals (type B) containing clear vesicles and granular vesicles 600 to 1000 Å in diameter, possibly of aminergic type, are also encountered. These fibers are rare and can be seen only in the portion of the pars nervosa near the pars intermedia of the adenohypophysis.
Lastly, fibers and terminals containing only clear vesicles ranging from 250 to 400 Å (type C) are occasionally found.
Nerve endings are often formed by type A fibers on the perivascular space and on the perivascular processes of the ependymal cells and pituicytes. In agreement with recent findings available in the literature, the occurrence of synaptoid contacts between these terminals and both pituicytes and ependymal cells may confirm the active role of these cells in transport and release of neurosecretion.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Acher, A.: Evolution des hormones neurohypophysaires. In: Progress in endocrinology, p. 425–432 (C. Gual and F. J. G. Ebling, eds.). Amsterdam: Excerpta Medica Foundation 1969.
Bargmann, W., Lindner, E., Andres, K. H.: Über Synapsen an endokrinen Epithelzellen und die Definition sekretorischer Neurone. Untersuchungen an 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 gambelii. Z. Zellforsch. 69, 198–227 (1966).
Bindler, E., LaBella, F. S., Sanwall, M.: Isolated nerve endings (neurosecretosomes) from the posterior pituitary. J. Cell Biol. 34, 185–205 (1967).
Campbell, D. J., Holmes, R. L.: Further studies on the neurohypophysis of the hedgehog (Erinaceus europaeus). Z. Zellforsch. 75, 35–46 (1966).
Dent, J. N., Gupta, B. L.: Ultrastructural observations on the developmental cytology of the pituitary gland of the spotted newt. Gen. comp. Endocr. 8, 273–288 (1967).
Doerr-Schott, J.: Etude au microscope électronique de la neurohypophyse de Rana esculenta L. Z. Zellforsch. 111, 413–426 (1970).
Doerr-Schott, J., Follenius, E.: Identifications et localisations des fibres aminergiques dans l'éminence médiane de la Grenouille verte (Rana esculenta L.) par autoradiographie au microscope électronique. Z. Zellforsch. 111, 427–436 (1970).
Douglas, W. W., Nagasawa, J., Schulz, R.: Electron microscopic studies on the mechanism of secretion of posterior pituitary hormones and significance of microvesicles (synaptic vesicles): evidence of secretion by exocytosis and formation of microvesicles as a byproduct of this process. In: Subcellular organization and function in endocrine tissues, p. 353–379 (H. Heller and K. Lederis, eds.). Cambridge: Cambridge University Press 1971.
Fasolo, A., Franzoni, M. F.: The neurohypophysis of the crested newt. I. First ultrastructural observations on the nerve fibre components. Atti Accad. Sci. Torino, I Cl. Sci. Mat. Fis. Natur. 105, 585–591 (1971).
Follett, B. K., Heller, H.: The neurohypophysial hormones of lungfishes and amphibians. J. Physiol. (Lond.) 172, 92–106 (1964).
Gerschenfeld, H. M., Tramezzani, J. H., De Robertis, R.: Ultrastructure and function in neurohypophysis of the toad. Endocrinology 66, 741–762 (1960).
Green, J. D.: Vessels and nerves of amphibians hypophysis. Anat. Rec. 99, 21–53 (1947).
Heller, H.: Occurrence, storage and metabolism of oxytocin. In: Oxytocin, p. 3–23 (R. Caldeyro-Barcia and H. Heller, eds.). London: Pergamon Press 1961.
Heller, H., Lederis, K.: Density gradient centrifugation of hormone containing subcellular granules from rabbit neurohypophysis. J. Physiol. (Lond.) 158, 27–29 (1961).
Hennig, A.: Das Ausmessen räumlicher Strukturen mittels zufälliger Sonden (Punkten, Linien, Ebenen). In: Proceedings of Symposium on Quantitative Methods in Morphology (Weibel, E. R. and H. Elias, eds.). Berlin-Heidelberg-New York: Springer 1967.
Herlant, M.: Mode de libération des produits de neurosécrétion. In: Neurosecretion, p. 20–35 (F. Stutinsky, ed.). Berlin-Heidelberg-New York: Springer 1966.
Imai, Ch.: Histologische Untersuchungen an Zwischenhirnneurohypophysensystem von Megalobatrachus japonicus. Z. Zellforsch. 52, 501–505 (1960).
Kauz, S., Lederis, K.: Separation by density gradient centrifugation of different hormone granules from the trout neurohypophysial tissue. Gen. comp. Endocr. 5, abs. 56 (1965).
Knowles, F., Vollrath, L.: Synaptic contacts between neurosecretory fibers and pituicytes in the pituitary of the eel. Nature (Lond.) 206, 1168–1169 (1965).
Knowles, F., Vollrath, L.: A functional relationship between neurosecretory fibers and pituicytes in the eel. Nature (Lond.) 208, 1343 (1966).
Koelle, G. B.: A proposed dual neurohumoral role of acetylcholine. Its functions at the pre- and post-synaptic sites. Nature (Lond.) 190, 208–211 (1961).
La Bella, F. S., Beaulieu, G., Reiffenstein, R. J.: Evidence for the existence of separate vasopressin and oxytocin-containing granules in the neurohypophysis. Nature (Lond.) 193, 173 (1962).
Lederis, K.: Fine structure and hormone content of the hypothalamo-hypophysial system of the rainbow trout exposed to sea water. Gen. comp. Endocr. 4, 638–661 (1964).
Lederis, K.: Ultrastructural and biological evidence for the presence and likely functions of acetylcholine in the hypothalamo-neurohypophysial system. In: Neurosecretion p. 155–165 (F. Stutinsky, ed.). Berlin-Heidelberg-New York: Springer 1967.
Lederis, K., Livingston, A.: Subcellular localization of acetylcholine in the posterior pituitary of the rabbit. J. Physiol. (Lond.) 196, 348–368 (1968).
Livingston, A.: Subcellular aspects of storage and release of neurohypophysial hormones. J. Endocr. 49, 357–372 (1971).
Livingston, A., Lederis, K.: Functional ultrastructure of the neurohypophysis. In: Subcellular organization and function in endocrine tissues, p. 233–262 (H. Heller and K. Lederis, eds.). Cambridge: Cambridge University Press 1971.
Mazzi, V.: Sistema neurosecretorio ipotalamo-ipofisario, liquor ventricolare e adenoipofisi. Monit. zool. ital. 62 (Suppl.) 518–522 (1954).
Mazzi, V., Peyrot, A.: La eminenza mediale della neuroipofisi negli Anfibi urodeli. Monit. zool. ital. 64, 181–189 (1957).
Monroe, B. G., Scott, D. E.: Ultrastructural changes in the neural lobe of the hypophysis of the rat during lactation and suckling. J. Ultrastruct. Res. 14, 497–517 (1966).
Nakai, Y.: Electron microscopical observations on synapse-like contacts between pituicytes and different types of nerve fibers in the Anuran pars nervosa. Z. Zellforsch. 110, 27–39 (1970).
Nakai, Y., Gorbmann, A.: Evidence for a doubly innervated secretory unit in the Anuran pars intermedia. II. Electron microscopical study. Gen. comp. Endocr. 13, 108–116 (1969).
Palay, S. L.: The fine structure of the neurohypophysis. In: Ultrastructure and cellular chemistry of neural tissues, p. 31–49 (Waelsch, H., ed.). London: Cassel & Co., Ltd. 1957.
Peyrot, A.: La vascularisation de l'hypophyse du Triton crêté (Triturus cristatus carnifex Laur.) en conditions normales at après interruption de se connexions avec l'hypothalamus. Arch. Anat. micr. morph. exp. 49, 411–429 (1960).
Reynolds, E. Y.: The use of lead citrate at high pH as an electron-opaque stain in electron microscopy. J. Cell Biol. 17, 208–212 (1963).
Richerson, A. B., de Roos, R.: Comparative morphology of the neurohypophysis of the three life stage of the central newt (Notophthalmus viridescens louisianensis). Gen. comp. Endocr. 17, 256–267 (1971).
Rodríguez, E. M.: Fixation of the central nervous system by perfusion of the cerebral ventricles with a threefold aldehyde mixture. Brain Res. 15, 395–412 (1969).
Rodríguez, E. M.: The comparative morphology of neural lobe of species with different neurohypophysial hormones. In.: Subcellular organization and function in endocrine tissues, p. 263–293 (H. Heller, K. Lederis, eds.). Cambridge: Cambridge University Press 1971.
Rodríguez, E. M., La Pointe, J.: Histology and ultrastructure of the neural lobe of the lizard, Klauberina riversiana. Z. Zellforsch. 95, 37–57 (1969).
Sawyer, H. W.: Phylogenetic aspects of the neurohypophysial hormones. In: Neurohypophysial hormones and similar polypeptides, p. 717–747 (B. Berde, ed.). Berlin-Heidelberg-New York: Springer 1968.
Smoller, C.: Ultrastructural studies on the developing neurohypophysis of the pacific treefrog, Hyla regilla. Gen. comp. Endocr. 7, 44–73 (1966).
Venable, J., Coggeshall, R.: A simplified lead citrate stain for use in electron microscopy. J. Cell Biol. 25, 407 (1965).
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).
Wittkowski, W.: Synaptische Strukturen und Elementargranula in der Neurohypophyse des Meerschweinchens. Z. Zellforsch. 82, 434–485 (1967).
Zambrano, D., De Robertis, E.: Ultrastructural changes of the neurohypophysis of the rat after castration. Z. Zellforsch. 68, 14–25 (1968a).
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 (1968b).
Author information
Authors and Affiliations
Additional information
Work supported by a grant from the Consiglio Nazionale delle Ricerche.
We are gratefully indebted to Dr. G. Gendusa and P. Balbi for technical assistance, dr. G. E. Andreoletti for statistical analysis.
Rights and permissions
About this article
Cite this article
Fasolo, A., Franzoni, M.F. & Mazzi, V. The neurohypophysis of the crested newt. Z.Zellforsch 134, 367–382 (1972). https://doi.org/10.1007/BF00307172
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00307172