Summary
The effects of mating on the depletion of osmiophilic material from dense-core vesicles (DCV) within the external layer of the rabbit median eminence (ME) were investigated. Two different populations of DCV were demonstrated within the ME external layer of the non-mated control animals. A plot of the diameters of these vesicles showed two peaks, one at 90–100 nm, and the other at 120–130 nm. These two populations of DCV were found in separate axons and axon terminals in contact with, or near the perivascular spaces of, portal capillaries. Within these axons and terminals an occasional membrane profile or “vesicle ghost” was also observed.
The same two populations of DCV were evident in the ME external layer of animals that were sacrificed at 10 minutes post-coitus. In these experimental animals, the number and size of the smaller population of DCV were the same as those of the none-mated controls. However, there was an obvious decrease in the number of the large (120–130nm) DCV, together with a simultaneous marked increase in the number of “vesicle ghosts”. These ghosts had a mean diameter of 137±14 nm. On the basis of their size, it is suggested that the “vesicle ghosts” represent large DCV that have been depleted of their content following mating. Ultrastructural evidence for the depletion of osmiophilic material from the large DCV of mated animals is provided.
According to previous writers the smaller DCV within the ME are aminergic, whereas the larger DCV may contain releasing factors (RF). Our findings provide further morphological evidence to support this hypothesis. Furthermore, RF and biogenic amines appear to be contained within separate nerve terminals in the rabbit ME.
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References
Clattenburg, R. E.: Post-coital ultrastructural changes in the neurons of three nuclei and the median eminence of the rabbit hypothalamus (Ph. D. Thesis). London, Ontario: The University of Western Ontario 1972
Clattenburg, R. E., Singh, R. P., Montemurro, D. G.: Ultrastructural changes in the preoptic nucleus of the rabbit following coitus. Neuroendocrinology 8, 289–306 (1971).
Clattenburg, R. E., Singh, R. P., Montemurro, D. G.: Post-coital ultrastructural changes in neurons of the suprachiasmatic nucleus of the rabbit. Z. Zellforsch. 125, 448–459 (1972)
Clementi, F., Ceccarelli, B., Cerati, E., Demonte, M. L., Felici, M., Motta, M., Pecile, A.: Subcellular localization of neurotransmitters and releasing factors in the rat median eminence. J. Endocrinol. 48, 205–213 (1970)
Clementi, F., Ceccarelli, B., Cerati, E., Demonte, M. L., Pecile, A.: Subcellular organization of the median eminence. Adv. Cytopharm. 1, 331–342 (1971)
Crighton, D. B., Schneider, H.P.G., McCann, S. M.: Localization of LH-releasing factor in the hypothalamus and neurohypophysis as determined by an in vitro method. Endocrinology 87, 323–329 (1970)
Desjardins, C., Kirton, K. T., Hafs, H. D.: Anterior pituitary levels of FSH, LH, ACTH and prolactin after mating in female rabbits. Proc. Soc. exp. Biol. (N.Y.) 126, 23–26 (1967)
Duffy, P. E., Menefee, M.: Electron microscopic observations of neurosecretory granules, nerve and glial fibers, and blood vessels in the median eminence of the rabbit. Amer. J. Anat. 117, 251–286 (1965)
Flérko, B.: Hypothalamic control of hypophyseal gonadotrophic function. In: Hypothalamic control of the anterior pituitary (J. Szentágothai, B. Flérko, B. Mess and B. Halász, eds.), p. 192–256. Budapest: Akadémiai Kiadó 1962
Flérko, B.: Control of gonadotrophin secretion in the female. In: Neuroendocrinology (L. Martini and W. F. Ganong eds.), p. 613–668. New York: Academic Press 1966
Flérko, B.: Action of hormones on the neural mechanisms controlling gonadotrophin secretion. Arch. Anat. micr. Morph. exp. 56 (Suppl. 3–4), 446–457 (1967)
Fuxe, K.: Cellular localization of monoamines in the median eminence and the infundibular stem of some mammals. Z. Zellforsch. 61, 710–724 (1964)
Fuxe, K., Hökfelt, T.: Further evidence for the existence of tubero-infundibular dopamine neurons. Acta physiol. scand. 66, 243–244 (1967)
Fuxe, K., Hökfelt, T.: Monoamine afferent input to the hypothalamus and the dopamine afferent input to the median eminence. In: Progress in endocrinology (C. Gual ed.), p. 495–502. Amsterdam: Excerpta Medica Foundation, 1969
Fuxe, K., Hökfelt, T., Sundestedt, C.-D., Ahrén, K., Hamberger, L.: Amine turnover changes in the tubero-infundibular dopamine (DA) neurons in immature rats injected with PMS. Neuroendocrinology 10, 282–300 (1972)
Halász, B.: Endocrine function of hypothalamic islands. In: Progress in endocrinology (C. Gual ed.), p. 508–514. Amsterdam: Excerpta Medica Foundation 1969
Halász, B., Gorski, R. A.: Gonadotrophic hormone secretion in female rats after partial or total interruption of neural afferents to the medial basal hypothalamus. Endocrinology 80, 608–622 (1967)
Halász, B., Pupp, L.: Hormone secretion of the anterior pituitary gland after physical interruption of all nervous pathways to the hypophysiotrophic area. Endocrinology 77, 553–562 (1965)
Hilliard, J., Hayward, J. N., Sawyer, C. H.: Post-coital patterns of secretion of pituitary gonadotrophin and ovarian progestin in the rabbit. Endocrinology 75, 957–963 (1964)
Ishii, S.: Association of luteinizing hormone-releasing factor with granules separated from equine hypophyseal stalk. Endocrinology 86, 207–216 (1970a)
Ishii, S.: Isolation and identification of secretory vesicles in the axons of the equine median eminence. Gunma Symp. Endocr. 7, 1–11 (1970b)
Ishii, S.: Classification and idendification of neurosecretory granules in the median eminence. In: Brain-endocrine interaction (K. M. Knigge, D. E. Scott and A. Weindl eds.), p. 119–141. New York: S. Karger 1972
Ishii, S., Iwata, T., Kobayashi, H.: Granular localization of corticotrophin-releasing activity in horse hypophyseal stalk homogenate. Endocr. jap. 16, 171–177 (1969)
Jonsson, G., Fuxe, K., Hökfelt, T.: On the catecholamine innervation of the hypothalamus, with special reference to the median eminence. Brain Res. 40, 271–281 (1972)
Knigge, K. M., Scott, D. E.: Structure and function of the median eminence. Amer. J. Anat. 129, 223–244 (1970)
Kobayashi, H., Ishii, S.: The median eminence as storage site for releasing factors and other biologically active substances. In: Progress in endocrinology (C. Gual ed.), p. 548–554. Amsterdam: Excerpta Medica Foundation 1969
Kobayashi, H., Ishii, S.: Functional electron microscopy of the hypothalamic median eminence. Int. Rev. Cytol. 29, 281–381 (1970)
Kobayashi, H., Matsui, T.: Fine structure of the median eminence and its functional significance. In: Frontiers in neuroendocrinology (W. F. Ganong and L. Martini eds.), p. 3–46. New York: Oxford University Press 1969
Kobayashi, T., Kobayashi, T., Yamamoto, K., Kaibara, M., Ajika, K.: Electron microscopic observations of the axonal inclusions in rat median eminence. Endocr. jap. (Suppl. 1) 11–26 (1969)
Kordon, C., Glowinski, J.: Role of hypothalamic monoaminergic neurons in the gonadotrophin release-regulating mechanisms. Neuropharmacology 11, 153–162 (1972)
Mess, B.: Site and onset of production of releasing factors. In: Progress in endocrinology (C. Gual ed.), p. 564–570. Amsterdam: Excerpta Medica Foundation 1969
Mess, B., Martini, L.: The central nervous system and the secretion of anterior pituitary trophic hormones. In: Recent advances in endocrinology (W. H. T. James ed.), p. 1–49. London: J. & A. Churchill Ltd. 1968
Monroe, B. G., Scott, D. E.: Fine structural features of the neural lobe of the rat hypophysis during lactation and suckling. J. Ultrastruct. Res. 14, 497–517 (1966)
Peters, A.: The fixation of central nervous tissue and the analysis of electron micrographs of the neuropil, with special reference to the cerebral cortex. In: Contemporary research methods in neuroanatomy (W. J. H. Nauta and S. O. E. Ebbesson eds.), p. 56–76. Berlin-Heidelberg-New York: Springer-Verlag 1970
Rinne, P. K.: Ultrastructure of the median eminence of the rat. Z. Zellforsch. 74, 98–122 (1966)
Schneider, H. P. G., Crighton, D. B., McCann, S. M.: Suprachiasmatic LH-releasing factor. Neuroendocrinology 5, 271–280 (1969)
Scott, D. E.: Fine structural features of the neural lobe of the hypophysis of the rat with homozygous diabetes insipidus (Brattleboro strain). Neuroendocrinology 3, 156–176 (1968)
Szentágothai, J., Flérko, B., Mess, B., Halász, B.: Hypothalamic control of hypophyseal gonadotrophic function. In: Hypothalamic control of the anterior pituitary (J. Szentágothai, B. Flérko, B. Mess and B. Halász eds.), chap. IV, p. 249–342, Budapest: Akadémiai Kiadó 1968
Tejasen, T., Everett, J. W.: Surgical analysis of the preoptico-tuberal pathway controlling ovulatory release of gonatodrophins in the rat. Endocrinology 81, 1387–1396 (1967).
Tima, L.: On the site of production of releasing factors. Mem. Soc. Endocr. 19, 895–901 (1971)
Zambrano, D.: The arcuate complex of the female rat during the sexual cycle. Z. Zellforsch. 93, 560–570 (1969)
Zambrano, D., De Robertis, E.: The effect of castration upon the ultrastructure of the rat hypothalamus. II Arcuate nucleus and outer zone of the median eminence. Z. Zellforsch. 87, 409–421 (1968)
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This investigation was supported by grants to Drs. D. G. Montemurro and R. P. Singh from the Medical Research Council of Canada. The authors gratefully acknowledge the technical assistance of Miss A. Overweel and Mrs. S. Griffin.
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Clattenburg, R.E., Montemurro, D.G., Bruni, J.E. et al. Post-coital depletion of dense-core vesicles from the external layer of the rabbit median eminence. Z.Zellforsch 142, 27–36 (1973). https://doi.org/10.1007/BF00306702
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DOI: https://doi.org/10.1007/BF00306702