Distribution of androgen receptor in rat ovarian follicles undergoing atresia at the beginning of pregnancy

The immunohistochemical localisation of androgen receptor (AR) was investigated in a cohort of ovarian antral follicles developing, and subsequently undergoing atresia, in a hyperprolactinaemic milieu at the beginning of pregnancy in rats. Differentiation of the investigated follicles, observed during the first 5 days of pregnancy, was accompanied by a centripetal disappearance of androgen nuclear receptor in the granulosa layer, which did not include the cumulus oophorus complex and some antral granulosa cells. This pattern of decline resembled that typical of follicles maturing during the oestrous cycle but took longer to occur. The follicles did not ovulate and subsequently underwent atresia. The degeneration of some follicles was accompanied by a further loss of AR in the cumulus granulosa cells, but a strong positive AR immunoreaction persisted in the oocyte nucleoli. Some perinatal and early antral atretic follicles were found. In most cases their granulosa layers were AR-positive, although often only weakly. However, follicles with AR negative granulosa layers were also encountered. Nuclear immunolabelling for AR was positive in luteinized follicles. It can be concluded that follicular atresia involves changes in AR distribution which can be demonstrated as an abnormal depletion or persistence of AR.