Final answer:
Folliculogenesis is the multi-stage process of follicle development in the ovary, where primordial follicles mature into primary, secondary, and finally tertiary follicles before ovulation, regulated by hormones like FSH and LH.
Step-by-step explanation:
The process of folliculogenesis involves several stages of follicle development in the ovary, culminating in ovulation. It starts with the primordial follicles, which are in a resting state and can remain so for years. Beginning at puberty, responsiveness to recruitment signals leads to the transformation of primordial follicles into primary follicles characterized by a single layer of granulosa cells that proliferate and change from a flat to a cuboidal shape. As this occurs, primary follicles transition into secondary follicles, increasing in diameter and adding connective tissue, blood vessels, and theca cells, which work alongside granulosa cells to produce estrogens.
Secondary follicles continue to grow, forming a thin acellular membrane around the oocyte known as the zona pellucida and accumulating follicular fluid, eventually becoming tertiary follicles. Most tertiary follicles undergo atresia; however, typically one will survive and progress to ovulation, releasing its secondary oocyte.
Ovulation is the result of a mature follicle releasing an oocyte, which, if fertilized, can lead to pregnancy. The remaining follicle cells form the corpus luteum, which produces hormones vital for pregnancy maintenance. The entire folliculogenesis process is tightly regulated by hormones including FSH (follicle-stimulating hormone) and LH (luteinizing hormone).