MICROANATOMY

Detailed explanation-1: -At the onset of development, the granulosa cell layer that surrounds the oocyte increases in size and they begin estrogen production through FSH stimulation. FSH acts to initially propagate the beginning of estrogen synthesis; however, estrogen production becomes an autonomous process by granulosa cells.

Detailed explanation-2: -Granulosa cells of the ovulatory follicle are the major and virtually only source of estradiol in the follicular phase of the ovarian cycle and secrete estrogens in response to FSH.