Preovulatory Granulosa Cells and Steroidogenesis. An Ultrastructural Study in the Rhesus Monkey.

Granulosa cells of developing preovulatory follicles from ovaries of 6 rhesus monkeys were studied with the electron microscope. They did not contain the cytoplasmic structures known to be associated with steroidogenesis. Such structures were found only in the luteinized granulosa cells of atretic follicles in the preovulatory ovary. The preovulatory granulosa cells were rich in RNA, and the production of the liquor folliculi is probably their main function. The apparent contradiction between the present findings and those reported in incubation studies is discussed.