REGENERATION OF HYPOTHALAMIC NERVE FIBRES AFTER HYPOPHYSECTOMY IN THE GOAT

1970 ◽  
Vol 64 (4) ◽  
pp. 696-704 ◽  
Author(s):  
Peter M. Daniel ◽  
Marjorie M. L. Prichard
Keyword(s):  
Median Eminence ◽  
Distal Part ◽  
Neural Tissue ◽  
Neurosecretory Material ◽  
Pars Tuberalis ◽  
Posterior Lobe ◽  
Nerve Fibres ◽  
Traumatic Lesion ◽  
Paraventricular Nuclei ◽  
Regenerating Nerve

ABSTRACT In goats kept for several months after hypophysectomy it was found that the nerve fibres of the hypothalamo-neurohypophysial tract had regenerated. A posterior lobe-like organ had formed in the neural tissue of the median eminence just proximal to the site where the nerve tract had been severed when the pituitary gland was removed. This new, small, ectopic infundibular process was not only well innervated but also highly vascularised and it contained large amounts of neurosecretory material. Some of the regenerating nerve fibres had grown out from the nerve tract into pars tuberalis and the meninges; many of these nerve fibres carried neurosecretory material. In one goat, not hypophysectomized but with a traumatic lesion of the nerve tract in the pituitary stalk, regenerating nerve fibres had also grown down across the scar of the lesion to reinnervate the degenerate distal part of the nerve tract. Within the hypothalamus the loss of nerve cells was consistently greater in the supraoptic than in the paraventricular nuclei.

SOME LIGHT- AND ELECTRON-MICROSCOPICAL OBSERVATIONS ON THE PARS TUBERALIS OF THE PITUITARY GLAND OF THE RABBIT

1972 ◽  
Vol 54 (3) ◽  
pp. 505-511 ◽  
Author(s):  
E. CAMERON ◽  
C. L. FOSTER
Keyword(s):  
Interstitial Cell ◽  
Secretory Granules ◽  
The Other ◽  
Neurosecretory Material ◽  
Pars Tuberalis ◽  
Nerve Fibres ◽  
Microscopical Level ◽  
Electron Microscopical Level ◽  
Irregular Nucleus ◽  
Electron Microscopical

SUMMARY The cytological appearance of the pars tuberalis both at the light- and the electron-microscopical levels is described. Two main types of cell, one, which is designated the tuberalis cell, having a rounded contour, pale cytoplasm with a few small secretory granules of about 100 nm in diameter, many polyribosomes and a relatively large ovoid nucleus; and the other, the interstitial cell, with long processes often encircling tuberalis cells, an irregular nucleus and cytoplasm with abundant microfilaments about 10 nm in diameter were seen. Beaded nerve fibres and neurosecretory material were demonstrated in the pars tuberalis with chrome alum—haematoxylin, a finding confirmed at the electron-microscopical level where nerve fibres which appeared to be making contact with tuberalis cells and containing numerous microvesicles of about 50 nm in diameter were observed.

EFFECT OF HYPOTHALAMIC LESIONS ON PITUITARY MELANOCYTE-STIMULATING HORMONE

1967 ◽  
Vol 39 (4) ◽  
pp. 485-NP ◽  
Author(s):  
S. TALEISNIK ◽  
J. DE OLMOS ◽  
R. ORÍAS ◽  
MARÍA E. TOMATIS
Keyword(s):  
Median Eminence ◽  
Male Rats ◽  
Posterior Lobe ◽  
Melanocyte Stimulating Hormone ◽  
Mammillary Bodies ◽  
Hypothalamic Lesions ◽  
Paraventricular Nuclei ◽  
Inhibiting Factor ◽  
Electrolytic Lesions ◽  
Stimulating Hormone

SUMMARY The effect on the content of melanocyte-stimulating hormone (MSH) activity in the pituitary of electrolytic lesions placed in different regions of the hypothalamus was studied in male rats. Lesions in the paraventricular nuclei resulted, after 15 days, in a decrease of pituitary MSH activity to 20·4 ± 4·5%/mg. gland as compared with the controls, without changes in the weight of the hypophyses. In a group of animals in which the lesions failed to destroy the paraventricular nuclei completely the MSH activity in the pituitary was 66·4 ± 7·5% of that of controls and the weight of the gland was significantly higher. Hypothalamic lesions in the median eminence of the tuber cinereum produced 24 hr. later a decrease of pituitary MSH activity to 6·6 ± 0·8%, but 15 days later the values/mg. gland were almost normal. Lesions placed in the mammillary bodies or in the nucleus caudatus did not affect pituitary MSH content. Extracts of stalk-median eminence or posterior lobe from animals with lesions in the paraventricular nuclei, failed to show MSH-releasing factor as it is found in intact animals, nor did they contain MSH-release-inhibiting factor. The results support the concept that the paraventricular nuclei are involved in the control of pituitary MSH secretion and suggest that the MSH content of the disconnected hypophysis is to some degree regulated autonomously.

HYPOTHALAMO-NEUROHYPOPHYSIAL NEUROSECRETION AFTER THE EXTIRPATION OF VARIOUS ENDOCRINE GLANDS

1963 ◽  
Vol 42 (2) ◽  
pp. 293-299 ◽  
Author(s):  
H. Arko ◽  
E. Kivalo ◽  
U. K. Rinne
Keyword(s):  
Median Eminence ◽  
Vascular System ◽  
Pituitary Hormones ◽  
Bilateral Adrenalectomy ◽  
Neurosecretory Material ◽  
Experimental Conditions ◽  
Paraventricular Nuclei ◽  
Aldehyde Fuchsin ◽  
Hypophysial Portal

ABSTRACT The possible role of the hypothalamo-neurohypophysial system in regulating the release of the anterior pituitary hormones was studied in the rabbit and the rat. Thyroidectomy, gonadectomy and uni- and bilateral adrenalectomy were the experimental conditions used. The neurosecretory material (N. S. M.) was demonstrated by the aldehyde-fuchsin (AF) technique. Distinct differences were not seen in the different groups of rabbits on account of the great variation between individuals. In the rats, the thyroidectomy and gonadectomy groups often had slightly more N. S. M. in the median eminence around the portal vessels than the controls. Slight depletion of N. S. M. in the infundibular process was observed in unilaterally adrenalectomized rats. N. S. M. passing into the portal vascular system showed a tendency to increase. In the bilateral adrenalectomy group, N. S. M. was reduced in the supraoptic and paraventricular nuclei, in the hypothalamo-hypophysial tract and in the infundibular process. However, considerably more numerous neurosecretory nerve fibres passing towards the portal vessels than in the controls were found in the median eminence of this group. The conclusion drawn was that N. S. M. entering the hypophysial portal vessels in the median eminence may be of significance in the regulation of corticotrophin release.

THE RELATION BETWEEN THE HYPOTHALAMIC NEUROSECRETION AND THE CORTICOTROPHIN RELEASE IN EXPERIMENTAL CONDITIONS

1960 ◽  
Vol XXXIV (I) ◽  
pp. 8-18 ◽  
Author(s):  
E. Kivalo ◽  
U. K. Rinne
Keyword(s):  
Paraventricular Nucleus ◽  
Median Eminence ◽  
Supraoptic Nucleus ◽  
Acute Stress ◽  
Neurosecretory Material ◽  
Experimental Conditions ◽  
Hypothalamic Cells ◽  
The One ◽  
Hypophysial Portal ◽  
Acth Release

ABSTRACT Acute stress, chronic stress plus hydration, cortisone treatment, cortisone treatment plus dehydration were used as methods of investigation and the relation between the neurosecretory activity of the hypothalamic supraoptic nucleus and paraventricular nucleus and the neurosecretory material around the hypophysial portal vessels of the median eminence on the one hand and the corticotrophin release on the other hand, has been studied in the rat. Whereas stress stimulates both the activity of the above mentioned cells of the hypothalamus and the ACTH release, stress plus hydration causes a depression of these hypothalamic cells but nevertheless causes a marked ACTH release. Cortisone inhibits the activity of the cells in the supraoptic nucleus and the paraventricular nucleus as well as the ACTH release whereas cortisone plus dehydration causes stimulation but inhibits the ACTH release. In some stress and cortisone treatment groups the variations of the neurosecretory material around the hypophysial portal vessels and of the ACTH release were found to show a correlation. It is concluded that the activity of the cells of the supraoptic nucleus and the paraventricular nucleus and the ACTH release do not seem to have any definite connection, whereas some observations indicate that the neurosecretory material in the region of the median eminence around the hypophysial portal vessels may have some significance in ACTH release.

Histopathology of pituitary tumours

2011 ◽  
pp. 121-127
Author(s):  
Eva Horvath ◽  
Kalman Kovacs
Keyword(s):  
Mammalian Species ◽  
Cell Types ◽  
Pars Intermedia ◽  
Pars Tuberalis ◽  
Posterior Lobe ◽  
Human Pituitary ◽  
Human Pituitary Gland ◽  
Fibre Network ◽  
Pars Anterior ◽  
A Minor

The human pituitary gland consists of two major components: the adenohypophysis comprising the hormone producing cells of the pars anterior, pars intermedia, and pars tuberalis, and the neurohypophysis, also called pars nervosa or posterior lobe (1). In contrast to most mammalian species, the human gland has no anatomically distinct pars intermedia (2). The exclusively proopiomelanocortin (POMC)-producing cells of the pars intermedia are sandwiched between the anterior and posterior lobes in the majority of mammals, whereas in the human they are incorporated within the pars anterior, thereby constituting the pars distalis (3). The pars tuberalis is a minor upward extension of the adenohypophysis attached to the exterior of the lower pituitary stalk. In this chapter we deal only with adenohypophyseal tumours. Histologically, the adenohypophysis consists of a central median (or mucoid) wedge flanked by the two lateral wings. The hormone-producing cell types are distributed in an uneven, but characteristic manner. The cells are arranged within evenly sized acini surrounded by a delicate but well-defined reticulin fibre network giving the pituitary its distinct architecture (4). In the center of the acini is the long-neglected pituitary follicle composed of the agranular nonendocrine folliculo-stellate cells (5).

Melatonin Receptors in the Lamb Pars tuberalis/Median Eminence throughout the Day

1993 ◽  
Vol 58 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Vincent Piketty ◽  
Jean Pelletier
Keyword(s):  
Median Eminence ◽  
Melatonin Receptors ◽  
Pars Tuberalis

Mechanism of restoration of ACTH release in rats with long-term lesions of the paraventricular nuclei

1986 ◽  
Vol 111 (1) ◽  
pp. 75-82 ◽  
Author(s):  
J. Dohanics ◽  
G. Kapócs ◽  
T. Janáky ◽  
J. Z. Kiss ◽  
G. Rappay ◽  
...  
Keyword(s):  
Median Eminence ◽  
Plasma Concentrations ◽  
Plasma Acth ◽  
Corticotrophin Releasing Factor ◽  
Paraventricular Nuclei ◽  
Basal Plasma ◽  
Corticosterone Response ◽  
Intact Rats ◽  
Acth Release

ABSTRACT The effects of lesions in the paraventricular nucleus (PVN) on the adrenocortical response to ether stress were investigated in neurohypophysectomized and intact rats. During the first 4 days after placement of lesions in the PVN, the corticosterone response to ether stress was almost completely inhibited. It then gradually increased and, within 4–6 weeks of surgery, was restored to about 60% of that in sham-operated rats. Basal plasma concentrations of corticosterone were low in rats after placement of lesions in the PVN and/or after neurointermediate lobectomy (NILX). Corticosterone responses to ether stress were similar in groups submitted to PVN lesions and/or NILX, and lower than those in the appropriate sham-operated groups. In all lesioned groups, plasma ACTH concentrations after a combination of stressors (ether plus laparotomy) were also lower than those in the sham-operated groups. Six weeks after lesioning of the PVN, immunoreactive rat corticotrophin-releasing factor-41 (rCRF-41) concentrations in stalk-median eminence (SME) extract fell to about 5% of that in sham-operated rats, while immunoreactive arginine vasopressin (AVP) concentrations did not change. Immunohistochemistry revealed a substantial decrease in rCRF-41 immunostaining of the median eminence 6 weeks after lesioning of the PVN, though randomly located clusters of stained terminals were still seen in the whole rostro-caudal extent of the median eminence. A mixture containing synthetic rCRF-41 and AVP, in proportions similar to those in SME extracts from sham-operated rats, caused significantly less release of ACTH from anterior pituitary cell cultures than did SME extracts from sham-operated rats. Extracts of SME from PVN-lesioned rats released as much ACTH as a mixture containing synthetic rCRF-41 and AVP in proportions similar to those in the SME extracts from PVN-lesioned rats. Extracts of SME from either PVN-lesioned or sham-operated rats did not cause a significant increase in the amount of ACTH released when preincubated with antisera to both rCRF-41 and AVP. It is suggested that (1) the restoration of the adrenocortical reponse to ether stress, evident within a few days of placement of lesions in the PVN, occurs independently of neurohypophysial function; (2) the full corticosterone and ACTH response to ether or ether plus laparotomy stress requires not only an intact PVN but also an intact neurointermediate lobe; (3) SME extracts from sham-operated rats contain a factor(s) with the ability to potentiate the ACTHreleasing effect of rCRF-41 and AVP; and (4) the ACTH-releasing activity of SME extract obtained from rats with long-term PVN lesions is probably due to its remaininJ content of rCRF-41 and AVP. J. Endocr. (1986) 111, 75–82

CELLULAR LOCALIZATION OF A PROLACTIN-LIKE ANTIGEN IN THE RAT BRAIN

1979 ◽  
Vol 83 (2) ◽  
pp. 261-NP ◽  
Author(s):  
G. TOUBEAU ◽  
J. DESCLIN ◽  
M. PARMENTIER ◽  
J. L. PASTEELS
Keyword(s):  
Rat Brain ◽  
Cellular Localization ◽  
Female Rats ◽  
Nerve Fibres ◽  
Male And Female ◽  
Immunoreactive Material ◽  
Paraventricular Nuclei ◽  
Male And Female Rats ◽  
The Brain

The distribution of immunoreactive neurones and fibres was studied in rat brain using an antiserum to rat prolactin. Neurones containing the immunoreactive material were localized in the arcuate, ventromedial, premamillary, supraoptic and paraventricular nuclei of the hypothalamus. Immunoreactive nerve fibres were widely distributed within the brain. No differences were observed in labelling between male and female rats, or as a consequence of hypophysectomy.

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