Various endocrine factors may contribute to the phenomenon of arrested follicular development, which is the hallmark of anovulatory infertility in polycystic ovary syndrome. Hypersecretion of luteinizing hormone and/or insulin, together with high intrafollicular concentrations of androgens, can interact to produce supraphysiological levels of cyclic AMP in granulosa cells, resulting in premature activation of terminal differentiation and, hence, arrest of follicle growth.