Optimization of culture-preservation methods to maintain developmental competence in porcine MII oocytes post-IVM.

After in vitro maturation (IVM) of porcine germinal vesicle (GV) oocytes, those that matured to the metaphase II (MII) stage were selected for further culture over a period of 24-48 h. Subsequently, these oocytes were either parthenogenetically activated or used for somatic cell nuclear transfer (SCNT) to evaluate their in vitro developmental competence. Parthenogenetically activated MII oocytes developed to the blastocyst stage after 42 h of continuous culture, whereas SCNT oocytes reached the blastocyst stage within 30 h of culture. These findings suggest that porcine MII oocytes retain their developmental competence after extended in vitro culture exceeding 30 h. This study highlights the potential of prolonged culture in enhancing the utility of MII-stage oocytes for livestock applications and possibly for future advancements in human infertility treatments.