The microstructure of granulosa cells during follicular development in Zaocys dhumnades was observed.The results showed that prefollicle cells were similar to the free surface epithelium of germinal bed in morphology,size and acidophilia/basophilla.At primordial follicle stage oocytes were surrounded by prefollicle cells.At granulosa cell stage,prefollicle cells transformed into small-size cells.At stage Ⅲ,granulosa cells differentiated into three kinds of heterogeneous granulose cells which are different in morphology.At stage Ⅳ,the heterogeneous granulosa cells transformed into small-size homogeneous granulosa cells.In summary,the granulosa cells are derived from free surface epithelium of germinal bed,and homogeneous granulosa cells develop into heterogeneous ones,then back into homogeneous ones during follicle development in Z.dhumnades.