Supporting cells for the developing female gamete in the ovary. They are derived from the coelomic epithelial cells of the gonadal ridge. granulosa cells form a single layer around the OOCYTE in the primordial ovarian follicle and advance to form a multilayered cumulus oophorus surrounding the ovum in the Graafian follicle. The major functions of granulosa cells include the production of steroids and LH receptors (receptors, lh).