What causes anovulation in polycystic ovary syndrome?

Abstract Anovulation in polycystic ovary syndrome (PCOS) is characterised by arrest of antral follicles, a phenotype that can be rescued by increasing circulating concentrations of follicle stimulating hormone (FSH). Abnormalities of gonadotropin regulation, secretion and action have been implicated in the aetiology of anovulation, as well as local, intraovarian factors. Recent studies have implicated both central and intraovarian actions of anti-Mullerian hormone (AMH) in the aetiology of PCOS and in the mechanism of anovulation. It is likely that more than one pathway is involved, whether extrinsic or intrinsic to the ovary, but there appears to be an important role for androgen programming of both neuroendocrine and ovarian effects on ovarian follicular function.