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Ovarian follicle atresia is the periodic process in which immature ovarian follicles degenerate and are subsequently re-absorbed during the follicular phase of the menstrual cycle. Typically around 20 follicles mature each month and only a single follicle is ovulated. The rest undergo atresia. That single dominant follicle becomes a corpus luteum following ovulation.〔 〕 Atresia is a hormonally controlled apoptotic process that depends dominantly on granulosa cell apoptosis. To date, at least five cell-death ligand-receptor systems have been reported in granulosa cells to play a role in atresia regulation.〔 〕〔 They are: * tumor necrosis factor alpha (TNF alpha) and receptors * Fas ligand and receptors〔 * TNF-related apoptosis-inducing ligand (TRAIL; also called APO-2) and receptors * APO-3 ligand and receptors * PFG-5 ligand and receptors In addition, two intracellular inhibitor proteins, cellular FLICE-like inhibitory protein short form (cFLIPS) and long form (cFLIPL), which were strongly expressed in granulosa cells, may act as anti-apoptotic factors. It has been proposed that enhanced levels of Nitrogen oxide in rats can prevent atresia of the ovarian follicle, and depressed levels have the opposite effect. ==See also== *Folliculogenesis *Ovary *Ovarian reserve 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ovarian follicle atresia」の詳細全文を読む スポンサード リンク
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