Analysis of structure and function of folliculo-stellate cell in the anterior pituairy gland

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Folliculo-stellate cells (FS cells) in the anterior pituitary gland have been described as star-shaped cells with cytopolasmic processes extending between and surrounding neighboring glandular hormone-producing cells. FS cells are immunocytochemically positive for S-100 protein and GFAP.FS cells contain any secretary granules in their cytoplasm and appear quite different from the hormone-secreting cells. Previous studies have suggested that FS cells play a supportive role for the neighboring glandular cells. For the study of the function in anterior pituitary gland we established novel FS cell line (TtT/GF) from pituitary tumor. We studied about FS cell function and structure using TtT/GF and the FS cells in the anterior pituitary gland in castrated or aging animal. Result obtained as follows. 1) When both TtT/GF cells and growth hormone secreting pituitary tumor cell line (MtT/S) are implanted simultaneously into nude mice produced large growth hormone producing tumor in every animal. In contrast, when nude mice are implanted with MtT/S cell alone, or together with fibroblasts, either no tumors, or very small pituitary tumors were formed. Furthermore, implantation of TtT/GF cells alone produces no tumors.These data indicated the TtT/GF stimulate pituitary tumore formation in nude mice by secreting some growth factor or controlling microenvironment such as by angiogenesis. 2) FS cell produces number of colloid containing follicles in the aging animal. The wet weight of pituitary glands in those animals were 4 times bigger than those of the young animals. Interestingly the prolactin cells specifically appeared around of these follicles which suggests the existing some relationship between prolactin cell proliferation and FS cells in aging animals. 3) The FS cells are increased in number by castration in proportional to LH cell highperplasia which suggesting FS cells also stimulate the proliferation of castration cells in those animals.