scholarly journals Some Observations on the Cytology of the Adenohypophysis of the Non-parous Female Rabbit

1959 ◽  
Vol s3-100 (51) ◽  
pp. 463-482
Author(s):  
M. ALLANSON ◽  
C. L. FOSTER ◽  
G. MENZIES
Keyword(s):  
Proteolytic Enzymes ◽  
Portal System ◽  
Pars Intermedia ◽  
Pars Tuberalis ◽  
Pars Distalis ◽  
Electron Microscopic ◽  
Female Rabbit ◽  
Lipid Inclusions ◽  
Cytological Characteristics ◽  
Hypophysial Portal

Evidence is presented which suggests that in this animal the pars tuberalis may have some function in addition to acting as a bed for the hypophysial portal system, since its cells appear rich in RNA. The granules of the cells of the pars intermedia are shown to be PAS-positive, but this reaction, unlike that of the basiphil cells of the pars distalis proper and the zona tuberalis, is readily prevented by pretreatment of sections with proteolytic enzymes. A study of the basiphil cells of the pars distalis proper and of the zona tuberalis, based on cytological characteristics, size, and shape, provides some evidence for the existence of two, and possibly three, kinds of basiphil cell. The lipid inclusions of the adenohypophysial cells and their relationship to the Golgi elements are described, together with some brief preliminary observations upon the electron microscopic characteristics of acidophil and basiphil cells.

SOME OBSERVATIONS ON THE ULTRASTRUCTURE OF THE ADENOHYPOPHYSIS OF THE RABBIT

1965 ◽  
Vol 31 (3) ◽  
pp. 279-287 ◽  
Author(s):  
B. A. YOUNG ◽  
C. L. FOSTER ◽  
E. CAMERON
Keyword(s):  
Granular Cell ◽  
Pars Intermedia ◽  
Pars Tuberalis ◽  
Pars Distalis ◽  
Cell Type ◽  
Cytoplasmic Rna ◽  
Large Numbers ◽  
Predominant Cell Type ◽  
Relationship Of ◽  
The Relationship

SUMMARY The ultrastructure of the adenohypophysis of the rabbit is described preliminary to reporting changes after experimental procedures. Fixation by perfusing with gluteraldehyde enabled selected regions of the gland to be removed with accuracy. Separate descriptions of the pars distalis proper, zona tuberalis, pars tuberalis and pars intermedia are therefore included. In the pars distalis proper four types of granular cell were recognized although their function cannot be accurately determined. For convenience, therefore, they have been designated 1, 2, 3 and 4. In addition a fifth type of cell (type 5) is described which is also present in the other areas. This cell, as well as having possible phagocytic functions, appears to be concerned in the formation of a perivascular channel. Two types of cell are recognized in the zona tuberalis, which are similar in appearance to the 3 and 4 cells of the pars distalis, although not necessarily identical in function. The characteristic cells of the pars tuberalis are rich in cytoplasmic RNA and contain large numbers of intracellular fibrils. It is suggested that the ribosomes are concerned in the synthesis of a sedentary protein which may take the form of the microfibrils. The pars intermedia contains a predominant cell type with large granules of varying density. The relationship of these granules to the specific hormone is discussed.

The pars tuberalis of the hypophysis: a modulator of the pars distalis?

1992 ◽  
Vol 126 (4) ◽  
pp. 285-290 ◽  
Author(s):  
Werner H Wittkowski ◽  
Andreas H Schulze-Bonhage ◽  
Tobias M Böckers
Keyword(s):  
Close Contact ◽  
Melatonin Receptors ◽  
Portal System ◽  
Secretory Cells ◽  
Specific Cell ◽  
Pars Tuberalis ◽  
Pars Distalis ◽  
Functional Connection ◽  
Morphological Alterations ◽  
Functional Changes

The pineal hormone melatonin is known to influence circadian systems. Melatonin is also ascribed to mediate photoperiodic effects on the regulation of the hypothalamo-hypophyseal-gonadal axis. Other endocrine actions, especially a thyrotropic influence, have been postulated. Site and mechanism of action of melatonin, however, are still matters of speculation. In search of a functional cascade of (i) photoperiodic stimuli, (ii) their hormonal messenger melatonin, and (iii) endocrine targets, the pars tuberalis has gained a key position. The recent discovery and characterization of melatonin receptors located in the pars tuberalis of several species support such a functional significance. Earlier results point to a functional connection of the pars tuberalis with the pineal gland: the pars tuberalis is known for a pattern of differentiation distinctly different from other parts of the adenohypophysis. It contains a specific cell population with a morphology typical of peptide secreting cells. Like the hypothalamic nerve endings of the median eminence, they are in close contact with the primary plexus of the portal system. In contrast to secretory cells of the pars distalis, the specific cells of the pars tuberalis do not respond with morphological alterations to functional changes of peripheral endocrine glands. Yet, photoperiodic stimuli obviously influence morphology and functional activity of the pars tuberalis-specific cells. Investigations during recent years have led to the tentative conclusion that the pars tuberalis represents the hypophysial "receptor"for melatonin as the chemical messenger of photoperiodic stimuli. Depending on melatonin secretion pattern and melatonin receptivity, the pars tuberalis seems to modulate at least gonadotropic and thyrotropic activity of the pars distalis via a peptide hormone distributed in the pars distalis by the portal plexus. Such an intrahypophysial regulatory concept may explain the widespread actions of melatonin on endocrine targets.

The Pituitary Gland: Embryology, Physiology, and Pathophysiology

2000 ◽  
Vol 19 (2) ◽  
pp. 9-17 ◽  
Author(s):  
Angela Dorton
Keyword(s):  
Pituitary Gland ◽  
Anterior Pituitary ◽  
Pituitary Hormones ◽  
Thyroid Stimulating Hormone ◽  
The Body ◽  
Pars Intermedia ◽  
Pituitary Hormone ◽  
Pars Tuberalis ◽  
Pars Distalis ◽  
Stimulating Hormone

The pituitary gland, the “master gland” of the body, is composed of endocrine cells, which secrete hormones essential for homeostasis. The gland consists of the adenohypophysis (anterior pituitary) and the neurohypophysis (posterior pituitary), two unique structures that differ anatomically and functionally.The neurohypophysis is innervated by nerve cells in the hypothalamus and forms the connection between it and the pituitary gland. The hypothalamus stimulates release and inhibition of pituitary hormones. The neurohypophysis secretes oxytocin and antidiuretic hormone.The adenohypophysis is composed of three structures: the pars distalis, the pars intermedia, and the pars tuberalis. The anterior pituitary (pars distalis) is responsible for the release of hormones that include growth hormone, prolactin, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, adrenocorticotropic hormone, and melanocyte-stimulating hormone.Disorders of the pituitary are predominately those of insufficient hormone release and may have profound effects on the neonate. The potential causes of and clinical symptomatology that may accompany pituitary hormone insufficiency in the neonatal period are explored.

Changes in glucocorticoid receptor mRNA in the developing ovine pituitary and the effects of exogenous cortisol

1995 ◽  
Vol 144 (3) ◽  
pp. 483-490 ◽  
Author(s):  
S G Matthews ◽  
K Yang ◽  
J R G Challis
Keyword(s):  
Glucocorticoid Receptor ◽  
Late Gestation ◽  
Developmental Changes ◽  
Pars Intermedia ◽  
Pars Distalis ◽  
Short Term ◽  
Neonatal Life ◽  
Inferior Aspect ◽  
Glucocorticoid Receptor Mrna

Abstract Developmental changes in pituitary glucocorticoid receptor (GR) mRNA were examined during gestation and early neonatal life using in situ hybridization. Pituitaries were harvested from sheep fetuses at days 60–80, 100–120, 130–135, 140–142 and term, and from lambs of days 0–7 and 30–60, and adults. GR mRNA was present in the pars distalis by day 60, levels increased through gestation, and there was a redistribution of GR mRNA, resulting in a relatively greater abundance at the base of the pars distalis. At term, there was a significant (P<0·05 compared with the day 140–142 fetuses) elevation of GR mRNA, which was maintained in the newborn lamb, reaching highest levels at days 30–60 of neonatal life. GR mRNA was undetectable in the pars intermedia until day 120, but subsequently increased to high levels at term. Interestingly, the expression of GR mRNA in the pars intermedia dropped precipitously in the newborn (P<0·05 compared with term), though levels recovered in the older lambs and adults. The regional and cellular distribution of GR mRNA correlated closely with the presence of immuno-reactive GR (irGR) in the pituitary; the majority of irGR was present in the nuclei. Intrafetal infusion of cortisol (12 h; 5 μg/min) in late gestation (day 135) had no effect on GR mRNA expression in either the pars distalis or pars intermedia. These results indicated that, in the fetal pituitary, (1) the GR gene is expressed in both the pars distalis and pars intermedia, (2) levels of GR mRNA in the fetal pituitary correlated with the distribution of nuclear irGR, (3) GR mRNA is present at higher levels in the inferior aspect of the pars distalis, its abundance increases immediately prior to parturition and is maintained in the newborn, and (4) cortisol infusion for 12 h does not affect GR mRNA in either region of the pituitary, suggesting that, in the short term, glucocorticoids do not directly regulate GR synthesis. Journal of Endocrinology (1995) 144, 483–490

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).

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