impaired granulosa cell differentiation MP:0003357 MPheno.ontology atypical production of or inability to produce the supporting cells for the developing female gamete in the ovary of mammals; granulosa cells form a single layer around the mammalian oocyte in the primordial ovarian follicle and advance to form a multilayered cumulus oophorus surrounding the ovum in the Graafian follicle abnormal cell differentiation abnormal granulosa cell morphology