Localization of macrophages in the ovarian follicles during the follicular growth and postovulatory regression in chicken, Gallus domesticus

Macrophages may be a potential regulator of ovarian functions. The goal of this study was to determine the changes in the macrophage frequency (number of cells per unit square of tissue) during follicular growth, ovulation, and postovulatory follicular regression in chickens. Cryostat sections of ovarian stroma containing primary follicles, small white follicles, and preovulatory and postovulatory follicles of laying hens were immunostained for macrophage using mouse anti-chicken macrophage monoclonal antibody. Macrophages were observed under a light microscope and counted by a computer assisted image analyzer. The frequency of macrophages in the theca layer was significantly greater in the small white follicles than in the primary follicles (P < 0.01) and also greater in the preovulatory follicles than in the small white follicles (P < 0.01). No significant differences were observed in the macrophage frequency between the third largest and largest preovulatory follicles. Ln the theca layer of postovulatory follicles, macrophage frequency was significantly greater than in that layer in the preovulatory follicles (P < 0.01); however, the frequency of macrophages decreased significantly in the Day 3 postovulatory follicles as compared with Day 1 postovulatory follicle (P < 0.05). These results suggest that macrophages may play an important role in the follicular development and regression of postovulatory follicles.