The expansion of the cumulus granulosa cells ( cumulus oophorus ) occurs in mature ovarian follicles in response to the preovulatory increase of concentration of luteinizing hormone (LH ) in the blood . As a result of intensive extracellular matrix synthesis follicular cumulus oophorus cells move apart , the whole structure multiplies the initial volume , and finally torn off along with the oocyte from the follicle wall granulosa . Since the corona radiata cells have virtually no LH receptors , the drive signal to it tries to expand them through other molecules .