Abstract
The present study was carried out to examine ovarian response to a combination of pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG), oocyte maturation in vivo or in vitro, and the in vitro fertilization rate of in vivo and in vitro matured oocytes of prepubertal Jinhua pigs at 70-75 days of age. Eighteen of the 19 pigs treated with gonadotropins had follicles larger than or equal to 7 mm in diameter, and 4 pigs ovulated 36-42 h after hCG injection. The rate of nuclear maturation in the oocytes from large ( ?? 7 mm) follicles (81%) was similar to that in oocytes from small (2-6 mm) follicles of control animals and cultured in vitro (83%), and the rate of sperm penetration in oocytes matured in vivo (88%) did not differ significantly from that oocytes matured in vitro (97%). However, the rates of male pronucleus formation and monospermy were significantly higher in oocytes matured in vivo (89% and 31%) than in oocytes matured in vitro (56% and 9%). These results show that follicular oocytes in prepubertal Jinhua pigs at 70-75 days of age can mature equally in vivo and in vitro, but the fertilizability of oocytes matured in vivo is superior to that of oocytes matured in vitro.
