Figure 2.

Schematic presentation of the action of androgen hormones on early follicular development. The androgens produced by the growing follicles can promote the transition from (1) primordial to primary follicles and (2) from primary to secondary follicles through the amplification of the actions of the IGF-1 system and can also amplify the actions of follicle stimulating hormone (FSH) on the promotion of the subsequent growth of (3) preantral and (4) antral follicles.