Characterization and Distribution of Dendritic Cells and Tissue Macrophages in the Rat Ovary

Yoon, Sik; Choi, Yeon Joo; Ko, Su Young; Park, Sun Mi; Park, Bong Soo

Abstract

This study was undertaken to investigate the characterization and distribution patterns of MHC class II positive dendritic cells[DCs] and ED2 positive tissue macrophages throughout the estrous cycle and during pregnancy in the rat ovary. The immunohistochemical characterization of the cells was carried out using the monoclonal antibodies OX6 and ED2 in cryostat-cut sections. DCs were distributed in the theca cell layer of the growing and mature follicles,stroma and corpus luteum. Tissue macrophages were distributed in the theca externa of the growing and mature follicles, stroma and corpus luteum but they were smaller in number than DCs. None of DC and tissue macrophage was found in the ovum, granulosa layer and follicular cavity of the ovarian follicle. However, DCs and tissue macrophages were present in the granulosa layer and follicular cavity in the atretic follicles. Degenerating corpus luteum contained a vast number of OX6 positive cells. On the contrary, fewer tissue macrophages were founcl in the degenerating corpus luteum. More macrophages tended to be observed in the former follicular cavity and theca lutein cell layer than in the granulosa lutein cell layer of the corpus luteum. In stroma,DCs and tissue macrophages were more frequently found around the blood vessels than in the other region, however, DCs were relatively greater in number than tissue macrophages. There was no estrous cycle and pregnancy dependent variation in the numbers and distribution patterns of DCs and tissue macrophages. In conclusion, the rat ovary contains rich networks of MHC class II positive dendritic cells and ED2 positive tissue macrophages. These findings suggest the existence of a well-developed system of immunological surveillance in the rat ovary. The results of this study have potentially important implications for the understanding not only of the ovarian immune system and the pathogenesis of various ovarian diseases but also of various physiologic functions of the ovary.