Abstract
Oocyte-cumulus cells connected to some of the parietal granulosa cells (OCG complexes) were mechanically obtained from pig early antral follicles 0.5-0.7 mm in diameter and were cultured for 8 days in collagen gels. The effects of FSH, dbcAMP, estradiol-17β (E2) and EGF on antrum formation in the OCG complexes were studied. After 1 day of culture, every OCG complex formed a spherical compact structure. The OCG complexes which had undergone FSH and dbcAMP treatment then formed antra, resulting in antral follicle-like structures, but no antra were formed in the E2, EGF-treated and control groups. Instead, in these groups the granulosa cells spread away from the oocytes. Proteins similar to those in pig follicular fluid were accumulated in the antral follicle-like structures of the OCG complexes induced by FSH and dbcAMP stimulation. These results indicate that mediated by cAMP rather than estrogen, FSH induces antrum formation in pig granulosa cells, and that EGF itself does not induce antrum formation in vitro.
