Localization of c-kit and stem cell factor (SCF) in ovarian follicular epithelium of a lizard, Podarcis s. sicula

We performed an immunohistochemical study to determine the immunolocalization of c-kit and stem cell factor (SCF) in ovarian follicles during the reproductive cycle of the lizard, Podarcis s. sicula. Follicles were serially cut and used for histological and histochemical characterization and also for immunohistochemical detection of both c-kit and SCF. C-kit and SCF were localized in the follicles with a differing pattern with regard to the stage of sexual cycle or the cell type forming the follicular epithelium (granulosa). In pre-reproductive follicles, where the granulosa consists of three main different cytotypes, the c-kit receptor was prevalently localized on the plasmalemma of small cells, although some pyriform and intermediate cells also appeared positive. C-kit was also localized in the theca. In pre-reproductive follicles, SCF was markedly observed in the cytoplasm of some pyriform cells. Small cells and theca also stained moderately positive, whereas the intermediate cells were mostly negative. In reproductive follicles, where granulosa cells are morphologically rearranged, c-kit was observed in small cells and in some thecal elements, while SCF was weakly immunostained. At the site of follicular layer invaginations evident c-kit/SCF immunostaining was observed in the granulosa epithelium and in the theca. These observations suggest that the expression of c-kit and SCF changes as a function of follicular development and may reflect the involvement of this system in the maturation of the oocyte.