follicle-stimulating hormone(redirected from Follitropin alfa)
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follicle-stimulating hormone(FSH): see gonadotropic hormonegonadotropic hormone
any one of three glycoprotein (see protein) hormones released by either the anterior pituitary gland or the placenta (the organ in which maternal and fetal blood exchange nutrients and waste products) that have various effects upon
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(FSH), a gonado-trophic hormone in man and other vertebrates produced by the anterior pituitary.
Chemically, the hormone is a glycoprotein; its primary structure has not been established. The molecular weight of FSH in sheep is 67,000; the molecular weight for swine is 29,000. The molecule consists of two subunits, alpha and beta. The alpha sub-unit is similar to the alpha subunits of luteinizing and thyrotropic hormones, whereas the beta subunit differs from the beta subunits of these hormones. The biological properties of FSH are determined solely by the beta subunit (in lizards, the beta subunit is as active as the native hormone). In females, FSH stimulates the development of follicles up to ovulation and promotes the growth of ovarian interstitial tissue; these effects lead to an increase in the secretion of female sex hormones, or estrogens. In males, FSH promotes the growth of the seminiferous tubules and stimulates spermatogenesis and the secretion of male sex hormones, or androgens. FSH acts jointly with the luteinizing hormone.
The synthesis and excretion of FSH are regulated both by the FSH releasing factor, which is elaborated by the hypothalamus, and by the levels of androgen and estrogen in the blood; as the concentrations of androgen and estrogen increase, the secretion of FSH decreases.
REFERENCESPankov, Iu. A. “Struktura i svoistva gipofizarnykh gormonov,” part 2: “Belkovye gormony gipofiza.” Problemy endokrinologii, 1974, vol. 20, no. 3.
Pierce, J G. “Properties of Pituitary Thyroid-stimulating Hormone in Comparison With Those of the Gonadotropins.” Biochemical Society Transactions, 1974, vol. 2, no. 5.
V. M. SAMSONOVA