Final answer:
Early follicular development is dependent on FSH, which stimulates the growth of the follicles, and LH also plays a role in estrogen production and triggering ovulation of the dominant follicle.
Step-by-step explanation:
The development of ovarian follicles is a complex process regulated by the interplay of several hormones, including Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). During the early stages of the follicular phase, FSH is crucial for stimulating the growth of several follicles. As follicles develop and become larger, with more granulosa and theca cells, they produce more estrogen in response to LH. This rise in estrogen, following negative feedback, will lead to a reduction in the levels of GnRH, LH, and FSH, subsequently causing most developing tertiary follicles to undergo atresia, leaving typically only one dominant follicle that will proceed to ovulation.
During the ovulation phase, a surge in LH, triggered by positive feedback from the elevated estrogen production by the dominant follicle, stimulates the final maturation and subsequent release of an oocyte from that dominant follicle. Thus, while the early development of follicles is FSH-dependent, the presence and actions of LH are also necessary for the production of estrogen and the eventual triggering of ovulation.