The rostral pars distalis of the pituitary gland of the freshwater and marine alewife (Alosa pseudoharengus)

1973 ◽  
Vol 141 (2) ◽  
pp. 145-159 ◽  
Author(s):  
H. Cook ◽  
J. J. Rusthoven ◽  
N. J. Vogelzang
Keyword(s):  
Pituitary Gland ◽  
Alosa Pseudoharengus ◽  
Pars Distalis ◽  
Rostral Pars Distalis

Characterization of pituitary IGF-I receptors: modulation of prolactin and growth hormone

2002 ◽  
Vol 283 (2) ◽  
pp. R468-R476 ◽  
Author(s):  
Shira Fruchtman ◽  
Douglas C. McVey ◽  
Russell J. Borski
Keyword(s):  
Growth Hormone ◽  
Pituitary Gland ◽  
Morone Saxatilis ◽  
Pars Distalis ◽  
Gh Secretion ◽  
High Affinity ◽  
Igf I ◽  
Similar Affinity ◽  
Rostral Pars Distalis

There have been no studies in any vertebrate that have localized insulin-like growth factor (IGF)-I receptors in prolactin (PRL) cells or that have correlated pituitary binding to the potency of IGF-I in regulating both PRL and growth hormone (GH) secretion. We show that IGF-I binds with high affinity and specificity to the pituitary gland of hybrid striped bass ( Morone saxatilis × M. chrysops). IGF-I and IGF-II were equipotent in inhibiting saturable125I-IGF-I binding, whereas insulin was ineffective. IGF-I binds with similar affinity to the rostral pars distalis (>95% PRL cells) as the whole pituitary gland and immunohistochemistry colocalizes IGF-I receptors and PRL in this same region. Des(1–3)IGF-I, a truncated analog of IGF-I that binds with high affinity to IGF-I receptors but weakly to IGF-I binding proteins (IGFBPs), showed a similar inhibition of saturable125I-IGF-I binding, but it was more potent than IGF-I in stimulating PRL and inhibiting GH release. These results are the first to localize IGF-I receptors to PRL cells, correlate IGF-I binding to its efficacy in regulating GH and PRL secretion, as well as demonstrate that IGFBPs may play a significant role in modulating the disparate actions of IGF-I on PRL and GH secretion.

Ultrastructure of the eta cells in the pituitary gland of adult migratory sockeye salmon (Oncorhynchus nerka)

1969 ◽  
Vol 47 (5) ◽  
pp. 937-941 ◽  
Author(s):  
H. Cook ◽  
A. P. van Overbeeke
Keyword(s):  
Endoplasmic Reticulum ◽  
Pituitary Gland ◽  
Sockeye Salmon ◽  
Secretory Granules ◽  
Oncorhynchus Nerka ◽  
Pars Distalis ◽  
Cell Type ◽  
Spawning Grounds ◽  
Predominant Cell Type ◽  
Rostral Pars Distalis

In the rostral pars distalis of the adult migratory sockeye salmon (Oncorhynchus nerka), most of the cells are arranged in follicles. The predominant cell type, the eta cell, contains secretory granules of 175–300 mμ in diameter; its endoplasmic reticulum shows a conspicuous lamellar organization. These cells undergo only slight changes as the fish migrate from the ocean to the spawning grounds. The findings are discussed in relation to the function of prolactin in euryhaline teleosts.

The vascularization and the neuroendocrine pathways of the pituitary gland in the Atlantic salmon, Salmo salar

1977 ◽  
Vol 55 (8) ◽  
pp. 1284-1296 ◽  
Author(s):  
G. Fridberg ◽  
B. Ekengren
Keyword(s):  
Atlantic Salmon ◽  
Pituitary Gland ◽  
Salmo Salar ◽  
Portal System ◽  
Secondary Development ◽  
Perivascular Spaces ◽  
Pars Distalis ◽  
Atlantic Salmon Salmo Salar ◽  
Intercellular Channels ◽  
Vascular Component

The pituitary gland of the Atlantic salmon, Salmo salar, is supplied by two arterial systems. The hypophysial arteries irrigate the rostral neurohypophysis and the pars distalis. The caudal hypothalamic arteries enter the neurointermediate lobe. In contrast with the capillary plexa in the neurohypophysis, the dorsal arteriol loops lack neurocrine terminals. An elaborate system of branches of the perivascular spaces extends into the neurohypophysis and it is continuous with the basement membrane in the neuroadenointerface and the intercellular channels of the pars distalis. This system is assumed to be an efficient conveyor of neurocrine factors and hypophysial hormones and an important vascular component. In the salmon the brain mediates its information to the pituitary through neurovascular links and the cells of the adenohypophysis are not innervated.The rostral neurohypophysis fulfills all criteria of being a median eminence although it lacks a well-defined portal system and it represents a secondary development from an original type seen in gnathostome vertebrates. It is suggested that the direct innervation of the endocrine cells in the pars distalis is a specialization and appeared late in the evolution of the teleost pituitary.

PERFUSION OF INTERCELLULAR SPACES IN THE PARS DISTALIS AND THEIR VARIATION WITH TIME OF DAY

1975 ◽  
Vol 66 (3) ◽  
pp. 385-NP
Author(s):  
W. B. QUAY
Keyword(s):  
Pituitary Gland ◽  
Functional Significance ◽  
Time Of Day ◽  
Male Rats ◽  
Pars Distalis ◽  
Intercellular Spaces ◽  
India Ink ◽  
Structural Regularity ◽  
Rat Pituitary ◽  
Light Darkness

SUMMARY Microperfusion of the tissue parenchyma of regions of the rat pituitary gland with 1:1 dilutions of India ink revealed a network of fine intercellular spaces or canaliculi throughout the pars distalis. They were demonstrable in animals of all ages from 1·5 months to over 1 year, in both sexes, and at various times during the 24 h light–darkness cycle. However, 24 h rhythms were suggested in the radial perfusion distance (P < 0·05) and tissue density (P < 0·01) of the perfused canaliculi in adult male rats. The amplitude of the 24 h rhythmicity in these pituitary canaliculi was lower than that shown recently in pineal canaliculi of the same species. Structural regularity and evidence of rhythmic and physiologically correlated changes in the pituitary canaliculi suggest that they relate to natural features rather than being only artifactual, and that analysis of their possible functional significance is appropriate.

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