Follicular expression of c-Kit/SCF and inhibin-alpha in mouse ovary during development

The mechanism of development of the ovarian follicles has been largely unknown. We performed an immunohistochemical (IHC) study to determine the follicular expressions of c-kit, SCF, and inhibin-alpha at different developmental stages in mouse ovary. Ovaries were obtained from 14 and 16 days post coitum and 2, 7, and 21 days post partum (dpp) mice. IHC for c-kit, SCF, and inhibin-alpha was carried out. c-Kit and SCF were expressed on oogonia regardless of the developmental stage. Immunoreactive c-kit and SCF antigens were expressed on oocytes of primordial and primary follicles of neonate mouse ovaries. In 21 dpp mouse ovary, the expression of c-kit/SCF in oocytes gradually decreased as the follicles developed. c-Kit/SCF was expressed strongly in oocytes of preantral follicles and weakly in granulosa and thecal cells. Inhibin-alpha was mainly expressed on granulosa cells of preantral and early antral follicles of the 21 dpp mouse ovaries. These findings suggest that the IHC expression of c-kit/SCF proteins is specific in all developmental stages of ovarian follicles and is decreased after the follicle starts to grow. The expression of inhibin-alpha is negatively correlated with the expression of c-kit/SCF in the ovarian follicles in mice.