SECRETORY CHANGES IN THE MUCOID CELLS OF THE ANTERIOR PITUITARY

SUMMARY With the object of obtaining basic information concerning the establishment of the feedback mechanism between the ovaries and the diencephalic-hypophysial system (DHS), changes in the gonadotrophic activity and histological structure of the anterior pituitary lobe were determined in groups of rats 21 days following ovariectomy on the day of birth or at 5, 10, 15, 20, 30 and 50 days. It was shown that the gonadotrophic activity of the hypophysis of spayed females and non-spayed controls differed using the criterion of uterine weight of the recipient, following ovariectomy at birth. After spaying at the age of 5 days the difference was also statistically significant using the criterion of ovarian weight. Histological investigation showed that in animals ovariectomized at days 1 and 5 there was an increase in PAS-positive mucoid cells in the adenohypophysis with a distinct PAS-positive Golgi zone in the pale centre of the cytoplasm. The results of these experiments show that a feedback mechanism between the ovaries and the DHS becomes established at an age between (21–x) and (26–x) days, where x is the period necessary for the development of demonstrable post-castration changes in the anterior lobe. In view of the reported initiation of ovarian oestrogen production, the hypothesis is discussed that the feedback mechanism begins to function during very early post-natal life.

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Sites of Insulin Action Using Ferritin Labeling

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066759 ◽

1971 ◽

Vol 29 ◽

pp. 540-541

Author(s):

Burton B. Silver ◽

Ronald S. Nelson

Keyword(s):

Electron Microscopy ◽

Binding Sites ◽

Anterior Pituitary ◽

Insulin Action ◽

Diabetic Rats ◽

Insulin Antibody ◽

Fat Pad ◽

Target Organs ◽

Uranium Salts ◽

Sugar Levels

Some investigators feel that insulin does not enter cells but exerts its influence in some manner on the cell surface. Ferritin labeling of insulin and insulin antibody was used to determine if binding sites of insulin to specific target organs could be seen with electron microscopy.Alloxanized rats were considered diabetic if blood sugar levels were in excess of 300 mg %. Test reagents included ferritin, ferritin labeled insulin, and ferritin labeled insulin antibody. Target organs examined were were diaphragm, kidney, gastrocnemius, fat pad, liver and anterior pituitary. Reagents were administered through the left common carotid. Survival time was at least one hour in test animals. Tissue incubation studies were also done in normal as well as diabetic rats. Specimens were fixed in gluteraldehyde and osmium followed by staining with lead and uranium salts. Some tissues were not stained.

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Effects of Hypophysectomy on the Fine Structure of Rat Liver Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060799 ◽

1967 ◽

Vol 25 ◽

pp. 156-157

Author(s):

Robert R. Cardell

Keyword(s):

Electron Microscopy ◽

Fine Structure ◽

Rat Liver ◽

Liver Cell ◽

Anterior Pituitary ◽

Liver Cells ◽

Biochemical Studies ◽

Liver Functions ◽

Rat Liver Cells ◽

And Control

Hypophysectomy of the rat renders this animal deficient in the hormones of the anterior pituitary gland, thus causing many primary and secondary hormonal effects on basic liver functions. Biochemical studies of these alterations in the rat liver cell are quite extensive; however, relatively few morphological observations on such cells have been recorded. Because the available biochemical information was derived mostly from disrupted and fractionated liver cells, it seemed desirable to examine the problem with the techniques of electron microscopy in order to see what changes are apparent in the intact liver cell after hypophysectomy. Accordingly, liver cells from rats which had been hypophysectomized 5-120 days before sacrifice were studied. Sham-operated rats served as controls and both hypophysectomized and control rats were fasted 15 hours before sacrifice.

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Pinocytotic-Like Forms of Mitochondria From Rat Anterior Pituitary

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100470 ◽

1968 ◽

Vol 26 ◽

pp. 146-147

Author(s):

Burton B. Silver

Keyword(s):

Electron Micrographs ◽

Conformational Changes ◽

Anterior Pituitary ◽

Dynamic State ◽

Surrounding Cell ◽

The Matrix ◽

The Moment ◽

Cell Medium ◽

Sectioned Tissue ◽

State Of Activity

Sectioned tissue rarely indicates evidence of what is probably a highly dynamic state of activity in mitochondria which have been reported to undergo a variety of movements such as streaming, divisions and coalescence. Recently, mitochondria from the rat anterior pituitary have been fixed in a variety of configurations which suggest that conformational changes were occurring at the moment of fixation. Pinocytotic-like vacuoles which may be taking in or expelling materials from the surrounding cell medium, appear to be forming in some of the mitochondria. In some cases, pores extend into the matrix of the mitochondria. In other forms, the remains of what seems to be pinched off vacuoles are evident in the mitochondrial interior. Dense materials, resembling secretory droplets, appear at the junction of the pores and the cytoplasm. The droplets are similar to the secretory materials commonly identified in electron micrographs of the anterior pituitary.

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Morphometric SEM study of the effects of ACTH on endothelial fenestrae in the rat adrenal cortex

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111288 ◽

1984 ◽

Vol 42 ◽

pp. 234-235

Author(s):

J. Curtis ◽

K. S. Schwartz ◽

R. P. Apkarian

Keyword(s):

Anterior Pituitary ◽

Lipid Droplets ◽

Adrenocorticotropic Hormone ◽

Unit Area ◽

High Density Lipoproteins ◽

Capillary Endothelium ◽

Zona Fasciculata ◽

Sem Study ◽

Saline Vehicle ◽

Scanning Electron

A scanning electron microscope (SEM) study was made of the effect of adrenocorticotropic hormone (ACTH) on the size and numbers of fenestrae/unit area in the capillary endothelium of the zona fasciculata (ZF) of the rat adrenal. The stimulatory effect of ACTH on cholesterol uptake via high density lipoproteins in the rat and evidence for the secretion of glucocorticoids by exocytosis of lipid droplets described by Rhodin suggest that endothelial change may accompany these transport phenomena.Twelve rats received two Dexamethasone (DEX) ip injections (25 μg DEX/100 g body wt.), the first at 8 PM and the second at 8 AM the next day, to inhibit the release of endogenous ACTH by the anterior pituitary. The animals were then divided into two groups. Six animals received only saline vehicle and six rats received ACTH (100 ng/100 g body wt.).

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An Electron Microscopic Study of the Acute Effects of Hypothalamic Releasing Factors on the Anterior Pituitary Gland

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100100901 ◽

1968 ◽

Vol 26 ◽

pp. 232-233

Author(s):

P.W. Coates ◽

E.A. Ashby ◽

L. Krulich ◽

A. Dhariwal ◽

S. McCann

Keyword(s):

Anterior Pituitary ◽

Microscopic Investigation ◽

Uranyl Acetate ◽

Electron Microscopic Investigation ◽

Electron Microscopic ◽

Tissue Samples ◽

Thin Sections ◽

Dense Membrane ◽

Membrane Bound ◽

Releasing Factors

The morphologic effects on somatotrophs of crude sheep hypothalamic extract prepared from stalk-median eminence were studied by electron microscopy in conjunction with concurrently run bioassays performed on the same tissue samples taken from young adult male Sherman rats.Groups were divided into uninjected controls and injected experimentals sacrificed at 5', 15', and 30' after injection. Half of each anterior pituitary was prepared for electron microscopic investigation, the other half for bioassay. Fixation using collidine buffered osmium tetroxide was followed by dehydration and embedment in Maraglas. Uranyl acetate and lead citrate were used as stains. Thin sections were examined in a Philips EM 200.Somatotrophs from uninjected controls appeared as described in the literature (Fig. 1). In addition to other components, these cells contained moderate numbers of spherical, electron-dense, membrane-bound granules approximately 350 millicrons in diameter.

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Ultrastructural morphology of nontumorous lactotrophs in human pituitaries exposed to high prolactin levels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100128766 ◽

1987 ◽

Vol 45 ◽

pp. 896-897

Author(s):

S. Jalalah ◽

K. Kovacs ◽

E. Horvath

Keyword(s):

Anterior Pituitary ◽

Secretory Activity ◽

Pituitary Hormones ◽

Feedback Mechanism ◽

Endocrine Activity ◽

Hormone Synthesis ◽

Anterior Pituitary Hormones ◽

Negative Feedback Mechanism ◽

Ultrastructural Morphology ◽

Transmission Electron

Lactotrophs, as many other endocrine cells, change their morphology in response to factors influencing their secretory activity. Secretion of prolactin (PRL) from lactotrophs, like that of other anterior pituitary hormones, is under the control of the hypothalamus. Unlike most anterior pituitary hormones, PRL has no apparent target gland which could modulate the endocrine activity of lactotrophs. It is generally agreed that PRL regulates its own release from lactotrophs via the short loop negative feedback mechanism exerted at the level of the hypothalamus or the pituitary. Accordingly, ultrastructural morphology of lactotrophs is not constant; it is changing in response to high PRL levels showing signs of suppressed hormone synthesis and secretion.By transmission electron microscopy and morphometry, we have studied the morphology of lactotrophs in nontumorous (NT) portions of 7 human pituitaries containing PRL-secreting adenoma; these lactotrophs were exposed to abnormally high PRL levels.

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