Ovarian follicles are the basic structural and functional unit of the mammalian ovary. Follicles contain an oocyte or female gamete, its surrounding granulosa cells, a basement membrane, and associated thecal cells. Development of the ovarian follicles from a small preantral follicle to the large pre-ovulatory follicle is key process in mammalian reproduction. From birth, ovary of the female contains a large number of immature, primordial/prenatral follicles. However, most of the follicles undergoes atresia and only few number of follicles reached to the ovulatory stage. The present knowledge...