Granulosa cells of the antral follicle at this stage normally respond to this early rise in A4 by increasing their aromatase activities, which is strongly counteracted by high AMH levels in the follicular microenvironment of the PCOS follicles, analogous to the AMH-FSH counteraction at later stages of follicular growth [17]. The gene discussed is AMH; the disease is polycystic ovary syndrome.