Aberrant follicle development and anovulation in polycystic ovary syndrome.

Endocrine factors appear to play an important part in arrest of antral follicle maturation in polycystic ovary syndrome (PCOS) but are unlikely to have an impact on early, preantral follicle development, which is clearly abnormal in PCOS. Disordered early folliculogenesis in PCOS is characterised by a higher proportion of follicles entering the growing phase and more prolonged survival of small follicles than in normal ovarian tissue. The factors responsible for aberrant preantral follicle development remain to be determined but IGFs, growth factors of the TGFbeta family and androgens may all have a role.