Folliculogenesis from the preantral follicle stage onwards will be dependent on gonadotropins, especially FSH. In turn, the secretion of these hormones is controlled by hypothalamic gonadotropin-releasing hormone (GnRH).
In the follicle, LH will stimulate the production of androgens by the theca cells. These hormones will be transformed into estrogens, thanks to FSH, in the granulosa cells. The large increase in serum estrogen concentration will trigger the mid-cycle ovulatory LH hormone peak.