Abstract
The objective of the present study was to evaluate the development to the blastocyst stage in vivo and in vitro of porcine oocytes matured and fertilized in vitro (IVM/IVF). When IVM/IVF oocytes had been transferred to oviducts of synchronized recipients just after IVF, more than 70% of blastocysts recovered after 6 days of transfer had developed to the hatched blastocyst stage with a mean cell number of 181.5 per blastocyst. In contrast, when IVM/IVF oocytes were cultured in vitro for 2 days and then transferred to the oviducts of recipients, or cultured in vitro for 6 days without transfer to oviducts, most recovered blastocysts were still enclosed by zona pellucidae. Mean cell numbers of blastocysts obtained from IVM/IVF oocytes cultured for 2 days in vitro plus 4 days in the oviducts and for 6 days in vitro decreased significantly (P<0.01) to 58.2 and 38.4, respectively, compared with that of blastocysts obtained from IVM/IVF oocytes cultured in oviducts for 6 days. These results suggest that porcine IVM/IVF oocytes have a high potential for developing to the blastocyst stage equal to that of in vivo matured oocytes and that the in vitro culture conditions used for IVM/IVF oocytes in the present study were suboptimal.
