Immunoelectron Microscopic Studies of Gonadotrophs in the Male and Female Rat Anterior Pituitaries, with Special Reference to their Changes with Aging.

Abstract

Summary.Gonadotrophs immunocytochemically identified with an antibody to LH/3 were studied in both male and female rats of various ages, viz., 2,14 and 23 months after birth. The rat gonadotrophs are classified into two cell types, i.e., Type I containing large (300-700 nm) and small Gonadotropins secreted by the anterior pituitaries of mammals are known to consist of two hormones, viz. the follicle-stimulating hormone (FSH) and luteinizing hormone (LH). In early morphological studies using either the light or electron microscope, gonadotropinproducing cells also divided into two types, suggesting that one might produce FSH and the other might produce LH (PURVES and GRIESBACH, 1954;FARQUHAR andRINEHART, 1954, 1955;BARNES, 1963;KUROSUMI and OOTA, 1968).BARNES (1963) demonstrated FSH cells and LH cells in the mouse anterior pituitary, and showed that the secretory granules of FSH cells were less electron dense than those of LH cells. KUROSUMI and OOTA (1968) found two groups of secretory granules, large and small, in rat presumptive FSH cells, but only small secretory granules in the putative LH cells. In mouse gonadotrophs, large secretory granules were not observed by BARNES (1963), though other morphological characteristics of rat and mouse FSH cells were identical. Immunohistochemistry at the light microscopic level revealed that most gonadotrophic cells in rat (NAKANE, 1970) and man (PHIFER et al., 1973) pituitaries contain both FSH and LH, though a few cells contain only one of these gonadotropins. Because of the colocalization of FSH and LH in some gonadotrophs, KUROSUMI (1974) renamed the previous FSH and LH cells Type I and Type II gonadotrophs, respectively. The authors use this classification here; that is, the Type I gonadotroph contains large and small secretory granules, while the Type II cell contains only small granules.As most typical gonadotrophs in the male rat pituitary that correspond to Type I gonadotrophs contain both LH and FSH in the same cell, the subcellular distribution of the two hormones required clarification. INOUE and KUROSUMI (1984) studied the immunoelectron microscopic localization of LB and 559

Pituitary Remodeling Throughout Life: Are Resident Stem Cells Involved?

“…Gonadotropes also show aging-associated changes. In the male rat pituitary, gonadotrope cell number and size decrease with a phenotypic shift from large to small vesicles in the cells, the latter being the main type present in the female gland (73,74). FSH and LH levels decrease with aging in male rats, whereas they remain constant or even rise in female rats.…”

“…FSH and LH levels decrease with aging in male rats, whereas they remain constant or even rise in female rats. Signs of degeneration (such as pyknosis) are observed in the aging gland gonadotropes (73). One of the best known aging-associated endocrine events is the so-called somatopause, a progressive fall in basal GH levels and resultant circulating IGF1 (75).…”

Gonadotropin-releasing hormone increases the release of extracellular vesicles from gonadotropes

“…To be sure that blebbing was not a feature of cells in a two-dimensional culture, electron microscopic examination of GnRHa-treated hemi-pituitaries was performed. In this instance, the gonadotropes were detected by their morphology, as described in classical texts (Kurosumi et al, 1991).…”

Pituitary Stem Cells: What We Know So Far (Part 2)

“…Somatostatin appeared to be increased in adulthood. FS cells (encompass SCs) decreased in number in rats but increased in humans [23,[27][28][29][30][31][32].…”