Fig. 2.

AMH actions in the hypothalamic–pituitary–gonadal (HPG) axis. Novel evidence shows that AMH can act centrally increasing the activity of GnRH neurons (a), which ultimately modulate GnRH/LH secretion. In the pituitary (b), AMH enhances FSH synthesis and elevates LH production following GnRH priming in the gland. AMH is mainly produced by the granulosa cells of small ovarian follicles in females (c). AMH actions within the ovaries control the small follicle growth and the selection of the dominant follicle. In males, AMH is mainly produced by Sertoli cells of the testes over embryonic and early postnatal period (d). Through paracrine actions, AMH drives the differentiation of the male internal genitalia and spermatogenesis. AMH also acts in Leydig cells controlling LH-mediated androgen production. Gonadal AMH levels may reach the brain and the pituitary to exert its endocrine actions; however, tissular AMH and AMH receptor expression indicate that autocrine regulations occur upstream in the HPG axis