REN and polycystic ovary syndrome: Since previous studies have shown strong immunostaining for renin and angiotensin in the theca cells and granulosa cells (GC) surrounding large cystic follicles in PCOS patients, while in normal ovarian follicular development, immunostaining is limited to the theca cell layer, except for follicles immediately before ovulation, which show strong staining for granulosa and theca cells [55], We hypothesized that RAS in granulosa cells may be responsible for promoting the overdevelopment of follicles in PCOS patients, resulting in the cystic appearance of follicles.