Fig. 2.

Schematic diagram of AMH regulation by FSH and E2 in GC of small and large antral follicles. Adapted from Grynberg M et al. JCEM, 2012 [65]. Until the small antral stage, AMH secretion is stimulated by different factors like FSH. Estradiol (E2) production under the influence of FSH is impaired by the inhibiting effect of AMH on aromatase. When estradiol concentration reaches a certain threshold in large antral follicles, it is capable of completely inhibiting AMH expression through ERβ, which predominates in growing follicles, thus overcoming the stimulation by FSH. In large follicles from PCO, the lack of FSH-induced E2 production and the high level of AMH impair the shift form the AMH to the E2 tone, thus leading to the follicular arrest