Histochemical Study of Follicles in the Senescent Porcine Pituitary Gland.

Abstract

Summary. Follicles displaying a positive periodic acidSchiff reaction to a colloid substance in the anterior pituitary gland have been observed in many vertebrates, including humans. It is also known that these follicles greatly increase in number and size with age. We therefore performed histochemical analysis of these colloid follicles in the senescent porcine pituitary gland in order to clarify their nature and biological significance. Results from various histological stains suggest that the colloid contains some polysaccharides or glycoproteins. In addition to the histological stains, lectin histochemistry revealed that the colloid contains sialic acid, N-acetyl galactosamine and galactose. Also, lectin staining indicated that some glycoproteins, most likely Asn-linked sialoglycoproteins, are localized in the colloid. The cells (FS cells) surrounding the colloid were densely stained with an antibody to S-100 protein but were not stained with antibodies to any other anterior pituitary hormones. Frequently mammotrophs (PRL cells), and occasionally gonadotrophs (LH cells) were found closely associated with folliculo-stellate cells ( FS cells) which lay next to the large colloid containing follicles. This suggests that not only are the FS cells important in the production of the colloids, but the adjacent LH and PRL cells in some way also contribute to their formation.Folliculo-stellate cells (FS cells) in the anterior pituitary gland were first described by RINEHART and FARQUHAR in 1953. FS cells were found to completely lack secretory granules and be further characterized by the presence of very long processes which surrounded adjacent glandular cells. The morphology of FS cells therefore suggests that they play an important role in the control of neighboring hormone secreting cells. Several functions have been proposed for FS cells.

Pituitary Pars Intermedia of Male Viscacha<i> (Lagostomus maximus maximus)</i>: A Morphometric Study of Seasonal and Age-Related Changes in Immunohistochemistry

“…Soji et al [1994] have shown an increase in the number of these cells in relation to age, suggesting that the expression of the S-100 protein indicates the cells` morphologic maturation stage in rats. The FSC in most pituitary glands of the studied species originated follicular structures with colloid in their lumen [Anthony and Gustafson, 1984;Ben-Jonathan et al, 1991;Kameda, 1991;Ogawa et al, 1996;Mohamed et al, 2000;Claudius et al, 2005]. In pigs and guinea pigs, a relation between the follicular colloid, the FSC and the pituitary hormone-secretory cells has been suggested [Kameda, 1991;Ogawa et al, 1997].…”

Extracellular Accumulations in the Avian Pituitary Gland: Histochemical Analysis in Two Species of Indian Wild Birds

“…A few studies on the mammalian pituitary also suggested a role for epithelial cells in colloid accumulation. Frequent occurrence of PRL cells and occasional LH cells in close association with stellate cells that lay next to the large colloid-containing follicles were reported, and it has been suggested that these cells in some way contribute to the formation of colloid [Ogawa et al, 1996]. Immunohistochemical study of epithelial cells in the PT of the human adult pituitary gland also elucidated that the colloid-forming follicular cells were mostly ACTH cells [Osamura and Watanabe, 1978].…”

“…Extracellular accumulations have been reported in the pituitary glands of all the vertebrate classes ranging from fish to mammals [Wingstrand, 1966;Holmes and Ball, 1974;Benjamin, 1981;Harrisson et al, 1982;Anthony and Gustafson, 1984;Ciocca et al, 1984;Dar and Sathyanesan, 1985;Kameda, 1991;Watanabe, 1991;Ogawa et al, 1996;Mohamed et al, 2000]. Accumulation of colloid in the follicular lumen and fibrous materials inside the cavities/cyst-like structures of the adenohypophysis have been reported in many vertebrates including the birds, though little information is available regarding their mode of formation, cellular types that take part in the formation of follicles or cysts, and the biological significance of these accumulations.…”

“…The accumulation of colloid takes place in the lumen of these follicles [Anthony and Gustafson, 1984;Ciocca et al, 1984]. Granulated epithelial cells of the pituitary gland, on the other hand, are mainly associated with the formation of epithelial cysts [Kameda, 1991;Watanabe, 1991;Ogawa et al, 1996]. The former structures are commonly referred to as colloid follicles, while the latter are given the name epithelial cysts.…”

“…These structures were named epithelial cysts [Benjamin, 1981;Kameda, 1991;Watanabe, 1991;Mohamed et al, 2000]. To understand the biological significance of extracellular accumulations in the pituitary gland, currently a few studies have been carried out employing conventional histochemical, biochemical, immunocytochemical and molecular biological techniques Boyd et al, 1986;Kameda, 1991;Ogawa et al, 1996Ogawa et al, , 1997Fleming et al, 1999;Mohamed et al, 2000;Inoue et al, 2002;Azzali et al, 2003]. These studies revealed the incidence of occurrence and mode of formation of colloid follicles/epithelial cysts, nature of follicle-building cells, distribution of colloid follicles/cysts in various parts of the pituitary gland and the chemical characterization of colloid.…”