Neurohypophysis. Structure and Function

Physiological and morphological identification of hypothalamic magnocellular neuroendocrine cells in goldfish preoptic nucleus*

“…Because single magnocellular neuroendocrine cells may contain several types of 'neurosecretory' vesicles, i.e. 'synaptic' ves cles and 'elementary' granules of different sizes and density (Bargmann, 1968;Ishi, 1972;Knowles & Vollrath, 1966;Leatherland & Dodd, 1967; Lederis, 1962;Perks, 1969;Raisman, 1973;Zambrano et al 1972) and may also send axonall' processes both as 'recurrent' collaterals to adjacent preoptic (Kandel, 1964), supraoptic (Dreifuss & Kelly, 1972;Hayward & Jennings, 1973a;Koizumi & Yamashita, 1972; and paraventricular (Moss, Dyball & Cross, 1972) neurones and as distant branches to the neurohypophysis and adenohypophysis (Bargmann, 1968;Knowles & Vollrath, 1966;Parry & Livett, 1973;Perks, 1969;Zambrano et al 1972) it is possible that some kind of 'selective' axoplasmic flow may divert particular intracytoplasmic neurosecretory elements at different rates to the different sites. At the present time the functional importance of multiple 'axonal' branches of vertebrate magnocellular neuroendocrine cells remains uncertain.…”

“…input (Hayward, 1972c(Hayward, , d, 1974 and send axonal processes along the hypothalamo-hypophysial tract to the median eminence (birds, Oksche, 1966;sheep, Parry & Livett, 1973), the pars intermedia (cat, Bargmann, 1968;teleost, Knowles & Vollrath, 1966;Perks, 1969; Zambrano, Nishioka & Bern, 1972) and to the neurohypophysial terminal neurohemal gland. Despite considerable anatomical (Bargmann, 1968;Cajal, 1911;Christ, 1966; Szentagothai, Flerko, Mess & Halasz, 1968), electrophysiological (Cross, 1973;Findlay & Hayward, 1969;Hayward, 1972cHayward, , d, 1974Hayward & Jennings, 1973a, b, c, d;Hayward & Vincent, 1970; Kandel, 1964) and chemical-pharmacological data (Ginsburg, 1968) on these magnocellular neuroendocrine cells only the classical Golgi study of Leontovich (1969) has provided some evidence about the morphology of dendritic arborization, the configuration of the somata and the numbers and types of axonal processes of these neurosecretory neurons. Now with the recent development of the fluorescent dye-marking technique (Stretton & Kravitz, 1968) a more precise delineation of different cell types, of connexions between dendrites of particular cells and the third ventricle, of the presence or absence of axone branching and collaterals and of the connexions between magnocellular neuroendocrine cells in the supraoptic and paraventricular nuclei and the extent to which magnocellular neuroendocrine cells send their axones to the median eminence, pars intermedia and pars distalis seemed possible.…”

“…Magnocellular neuroendocrine cell 'axones' may directly innervate not only the neurohypophysial neurohemal core (posterior pituitary gland) but also the median eminence (Oksche, 1966;Parry & Livett, 1973;Robinson & Zimmerman, 1973;Zimmerman et al 1973a), the glandular cells of the pars intermedia (Bargmann, 1968;Knowles & Vollrath, 1966;Perks, 1969;Zambrano et al 1972) and the circumventricular organs (Dierickx, 1962;Weindl, 1973) and cerebrospinal fluid (Heller et at. 1968;Robinson & Zimmerman, 1973;Vorherr et al 1968).…”

Central and Peripheral Catecholamine Innervation of the Rat Intermediate and Posterior Pituitary Lobes

“…Both lobes are heavily innervated [5,14,15,24); the intermediate lobe contains dopamine fibers with origin in the most rostral part of the arcuate nucleus [7]; the posterior lobe contains, in addition to its hypothalamic magnocellular-hypophyseal tract, numerous dopaminergic terminals, originating in the arcuate and periventricular nuclei [3,[6][7][8][9], and norepinephrine-containing fibers [I, 6, 11]. The origin of the norepinephrine innervation to the pos terior lobe has been alternatively postulated as exclusively of peripheral origin [8], of central origin [9], or mixed pe ripheral and central [1].…”

Exocytosis: The Common Release Mechanism of Secretory Granules in Glandular Cells, Neurosecretory Cells, Neurons and Paraneurons

“…One theory is molecular dispersion or diacrine secretion (PALAY, 1957;KUROSUMI, 1961;BARGMANN, 1968). According to this theory, the contents of the secretory granule are first extruded out of the granule and stored temporarily in the cytosol as a readily releasable intermediate pool.…”