Abstract
The surface ultrastructure of rat granulosa cells in culture was studied and correlated with progesterone secretion. Granulosa cells were harvested from pregnant mares’ serum-luteinizing hormone (PMS-LH) treated immature female rats and cultured on glass coverslips in Leighton tubes. Progesterone secretion as measured by specific radioimmunoassay and cell surface morphology utilizing routine procedures were studied in rat granulosa cell cultures under varying stimulatory and inhibitory conditions.