Follicular dynamics in the polycystic ovary syndrome

Anovulation in women with polycystic ovary syndrome (PCOS) is characterised by arrested growth of antral follicles. A relative lack of FSH may contrib ute to the persistence of anovulation but is unlikely, by itself, to be a m ajor cause of it. Granulosa cells from anovulatory women with polycystic ov aries hypersecrete oestradiol, compared with size-matched follicles from no rmal ovaries or polycystic ovaries from ovulatory women. This phenomenon ap pears to reflect a condition of advanced maturation of medium-sized antral follicles. The underlying basis for the abnormalities in anovulatory PCOS r emains uncertain, but it is possible that there are intrinsic differences i n folliculogenesis between polycystic and normal ovaries which affect prean tral as well as antral follicles. An alternative - but not mutually exclusi ve - explanation of this disorder is the abnormal endocrine environment. Hy persecretion of both LH and insulin are typical of anovulatory women with P COS. Studies in isolated granulosa cells, have shown, that insulin greatly augments the action of LH on steroidogenesis but this interaction may compr omise further growth of medium-sized antral follicles by generation of 'ple ovulatory' concentrations of cAMP within the granulosa cell and thereby lea ding, prematurely, to terminal differentiation of granulosa cells. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.