ABSTRACT
In this study, in order to further understanding of function of Mullerian inhibiting substance (MIS) and the ontogeny of the production profile of biologically active MIS and MIS type II receptor (MISR II), the patterns of their localization according to the follicular development in 21 ovarian specimens from women in reproductive age were studied by immunohistochemical staining. The flattened granulosa cells in primordial follicles failed to stain for MIS and MISR II, but the first staining was detected in the cuboidal granulosa cells in primary follicles. MIS and MISR II were detected specifically and exclusively in the cytoplasm of granulosa cells. The granulosa cells of both single and multiple layered growing preantral follicles showed strong specific staining for MIS and MISR II. Among the growing follicles, large follicle stained more intensely than small one. Within the multiple layers of granulosa cells, the innermost cells, closer to the oocyte, stained more intensely for MIS than those near the basement membrane, but MISR II was evenly distributed. In antral follicles, expression of the MIS was only seen in the granulosa cells, but MISR II was seen in the granulosa cells and theca cells. In large antral follicles, cumulus cells and periantral granulosa cells stained more intensely for MIS than those in the periphery. MIS staining waned in the mature follicles just before ovulation and could not be found in atretic follicles, corpus luteum, and corpus albicans. The expression levels of MISR II in mature follicles was lower than those in growing follicles and were even further reduced, but still detectable, in corpus luteum. There was a decreased level of MISR II expression when follicles become atretic and eventually lost from atretic follicles. The MIS and MISR II staining were not found in primordial follicles, oocytes, interstitial cells, ovarian epithelium, and corpus albicans. It is concluded that actions of MIS via MISR II are autocrine and paracrine in nature. The pattern of MIS and MISR II expression according to the menstrual cycles and development suggest that MIS may act as an intraovarian regulator of follicle maturation, selection and ovulation during the adult reproductive cycle.