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luteinizing hormone[′lüd·ē·ə‚nīz·iŋ ′hȯr‚mōn]
(LH; also, interstitial cell-stimulating hormone, or ICSH), one of the gonadotropic hormones secreted by the anterior pituitary.
Chemically, LH is a glycoprotein whose physical and chemical properties differ from species to species (in sheep, the molecular weight of LH is 40,000; in swine, 100,000). In females, LH stimulates the growth of the follicles in the stages preceding estrus and ovulation, in ovulation, and during the formation of the corpus luteum. A deficiency of LH in rats and guinea pigs leads to continuous estrus, a result of the abnormal enlargement of the follicles that did not undergo ovulation. The action of follicle-stimulating hormone (FSH) on the follicle is necessary before LH can exert its influence on the ovary. Ovulation, which is induced by LH, depends on the stage of follicular development, for which both the action time of LH and an optimal ratio of LH to FSH are important. For example, in cats and rabbits, the most effective ratio is 1:100. In males, LH stimulates interstitial testicular tissue and the secretion of the male sex hormone testosterone.
V. M. SAMSONOVA