Posted by Holly Todd on April 20, 2023 April 20, 2023 STEAM Projects Two models are shown: one will show the normal development of tertiary follicles and dominant follicles, and the other will show the disrupted development in a woman with PCOS related to hormone imbalances. This shows the follicular phase. As you can see, gonadotropin-releasing hormone (GnRH) stimulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH) production. In the case of PCOS, too much LH is produced, resulting in several more follicles. Continuing out the follicular phase, a dominant follicle produces estrogen, leading to a decrease in GnRH, LH, and FSH. In the ovary of a woman with PCOS, a dominant follicle does not emerge, and the regular estrogen production may not occur. This shows the beginning of the ovulatory phase. The dominant follicle survives in the follicular phase, secretes estrogen, and triggers a positive feedback loop in that causes LH and FSH production to rise again. For a woman with PCOS, this positive feedback loop is never triggered. During the luteal phase, the released oocyte travels towards the uterus while the granulosa and theca cells in the follicle form the corpus luteum, which produces progesterone. With PCOS, there is no corpus luteum and therefore no progesterone production.