The localization of Thy-1.1, MRC OX 2 and Ia antigens in the rat ovary and fallopian tube.

The localization of Thy-1, MRC OX 2 and Ia antigens as defined by monoclonal antibodies MRC OX 7, MRC OX 2 and MRC OX 6 was determined by an indirect immunoperoxidase technique on cryostat sections of rat ovaries. Thy-1 antigen was present significantly in the theca interna of growing antral follicles. Developing corpora lutea exhibited an increasing presence of Thy-1 antigen and it was still present in degenerating ones. Thy-1 antigen was constantly present in fallopian tube tunica propria. The MRC OX 2 antigen was expressed most on ovarian structures that do not develop further, i.e. granulosa of degenerating antral follicles and third generation of corpora lutea. MRC OX 2 antibody stained the capillaries of the fallopian tube; the most heavily MRC OX 2+ were the cells of ovarian germinal epithelium. The Ia+ cells were occasionally found within the growing ovarian structures but they were more frequent in degenerating ones. Rare or no la+ cells within the ovary and heavily Ia-depleted thymus medulla and Ia areas in the spleen were, however, observed in some rats. The role of these antigens with respect to the structures they label is discussed.