Fine structure of the median eminence and the pars nervosa of the bullfrog, Rana catesbeiana

1963 ◽  
Vol 60 (5) ◽  
pp. 667-687 ◽  
Author(s):  
Yoshihiko Oota ◽  
Hideshi Kobayashi
Keyword(s):  
Fine Structure ◽  
Median Eminence ◽  
Rana Catesbeiana ◽  
Pars Nervosa

Changes in the fine structure of tadpole (Rana catesbeiana) liver during thyroxine-induced metamorphosis

1970 ◽  
Vol 22 (2) ◽  
pp. 232-248 ◽  
Author(s):  
Thomas Peter Bennett ◽  
Janice S. Glenn ◽  
Huntington Sheldon
Keyword(s):  
Fine Structure ◽  
Rana Catesbeiana

HORMONAL CONTENT AND ULTRASTRUCTURE OF THE HYPOTHALAMO-NEUROHYPOPHYSIAL SYSTEM OF THE RAT AFTER INJECTION OF VINBLASTINE INTO THE MEDIAN EMINENCE

1977 ◽  
Vol 73 (2) ◽  
pp. 197-205 ◽  
Author(s):  
E. L. RODRÍGUEZ ◽  
ECHANDÍA, J. C. CAVICHIA ◽  
E. M. RODRÍGUEZ
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Median Eminence ◽  
Microscopic Analysis ◽  
Plasma Samples ◽  
Neural Lobe ◽  
Hormonal Content ◽  
Light Microscopic Analysis ◽  
Progressive Accumulation ◽  
Positive Materials

SUMMARY The effects of an injection of vinblastine (Vbl) into the median eminence on the structure, fine structure and antidiuretic hormone (ADH) content of the hypothalamo-neurohypophysial system in the rat is reported. The animals were studied on days 3, 8 and 25 after the injection of 1 or 5 mm-Vbl (3 μl). Significant changes were observed only in the 5 mm-Vbl-injected animals. Their median eminence extracts showed a progressive accumulation of ADH whereas ADH depletion occurred in the neural lobe extracts. On day 8 after injection, the animals exhibited strong polidipsia although considerable amounts of ADH still remained within the neural lobe. The ADH content of the plasma samples was consistently below the sensitivity of the method (5 μu.). The light microscopic analysis showed accumulation of Gomori-stainable products in the median eminence and a striking depletion of this material from the neural lobe. Electron microscopy revealed accumulation of neurosecretory vesicles and other inclusions proximal to the site of injection in the median eminence together with some evidence of nerve fibre degeneration. Few neurosecretory terminals were found in the neural lobe of the 8-day experimental rats. They had been engulfed by pituicytes for digestion. Recuperation of the normal ADH content of both median eminence and neural lobe was found to occur on day 25 after the Vbl injection. Simultaneously, the neural lobe refilled with Gomori-positive materials and neurosecretory terminals reappeared. The results suggest (1) reversible blockade of axoplasmic transport at the site of the Vbl injection; (2) reversible degeneration of neurosecretory terminals and (3) reversible blockade of ADH release in the surviving terminals of the neural lobe.

DISTRIBUTION OF CORTICOTROPHIN RELEASING FACTOR ACTIVITY WITHIN THE HYPOTHALAMIC-PITUITARY COMPLEX OF RATS AND CATTLE

1977 ◽  
Vol 75 (2) ◽  
pp. 293-303 ◽  
Author(s):  
NAOKI YASUDA ◽  
MONTE A. GREER ◽  
SUSAN E. GREER ◽  
PATRICIA PANTON
Keyword(s):  
Pituitary Gland ◽  
Dose Response ◽  
Median Eminence ◽  
Response Curve ◽  
Posterior Pituitary ◽  
Corticotrophin Releasing Factor ◽  
Pars Nervosa ◽  
Pituitary Glands ◽  
Posterior Pituitary Gland ◽  
Qualitative Similarity

An assay system involving cultured rat adenohypophysial cells from either intact or adrenalectomized donors was used to study the distribution of corticotrophin releasing factor (CRF) activity in the hypothalamic-pituitary complex of rats and cattle. In the rat hypothalamus, CRF activity was most concentrated in the median eminence, but CRF was present in the stalk and the posterior pituitary gland in much higher concentrations than in the median eminence in both species. The dose–response slopes for the median eminence, stalk and pars nervosa of the posterior pituitary gland were parallel to each other, suggesting a qualitative similarity between the CRF activity in these tissues. Rat posterior pituitary glands may also contain another CRF component which has a much flatter dose–response curve, but is detectable in smaller quantities of posterior pituitary tissue than is the other type of CRF.

CORTICOTROPHIC STUDIES WITH ASPIRIN

1962 ◽  
Vol 24 (1) ◽  
pp. 7-16 ◽  
Author(s):  
E. LEONG WAY ◽  
JOAN TAYLOR ◽  
L. J. OLD ◽  
R. GEORGE
Keyword(s):  
Ascorbic Acid ◽  
Antidiuretic Hormone ◽  
Median Eminence ◽  
Marked Reduction ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Pars Nervosa

SUMMARY The effect of aspirin in reducing adrenal ascorbic acid in Sprague—Dawley rats was studied using each animal as its own control. The response to aspirin was blocked by lesions in the region of the median eminence and by hypophysectomy. Removal of the pars nervosa also resulted in depression of the response in the majority of cases. In normal animals the dose of aspirin which produced marked reduction of adrenal ascorbic acid failed to promote antidiuresis. It was concluded that pituitary-adrenal activation by aspirin is mediated via the hypothalamus and that release of the antidiuretic hormone is not essential for this effect.

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