Reproduction Abstracts

The development of culture methods to produce oocytes from immature ovarian follicles in vitro would greatly contribute to livestock production and assisted human reproduction. However, successful in vitro culture to produce fully mature oocytes is very difficult in the case of large domestic animals. In the present study, we investigated the growth properties of in vitro-cultured porcine oocytes derived from early developmental stage follicles. Oocyte granulosa cell complexes (OGCs) were isolated from secondary follicles (250–300 μm in diameter) and individually cultured for 28 days. We examined antrum formation, the oocyte diameter, the chromatin configurations, the follicle cell numbers, and meiotic competence of the in vitro-cultured oocytes. During in vitro culture, the rate of antrum formation was the highest on day 14, and gradually decreased afterwards. The diameters of the oocytes increased during the culture period (from 75.5 to 112.7 μm) and was significantly and positively correlated with the number of follicle cells derived the OGCs (P<0.01), independent of the days in culture. As the culture progressed, the oocytes categorized as germinal vesicle (GV)1 increased in number, with a decrease in GV0 oocytes. At the end of the culture, oocytes derived from secondary follicles acquired meiotic competence. The cultured porcine oocytes, and may serve as a model for oocyte development for the propagation of large domestic animals.