[Some factors affecting in vitro development of porcine embryo reconstitution from somatic cells nuclear transfer]

In this paper, a study on reconstitution of porcine oocytes by using nuclear transfer with cumulus cells(CC) and fibroblast cells(FC) was carried out. Reconstituted oocytes which were the fusion with CC and showed a cleavage rate of 56.7%, developed to morula(11.7%) and blastocysts(6.7%) phases which were higher than those derived from the fusion with FC(p < 0.05). The results of this study also involved the effects of oocyte collection method and maturational age of recipient oocytes during the in vitro development of nuclear-transfer embryos which were reconstructed with cultured cumulus cells. The cumulus cells synchronized in G0/G1 phases through serum-starvation culture, were transferred into enucleated oocytes which were collected by aspiration or dissection method and cultured for 33 or 44 h. Reconstituted embryos were activated with a combination of calcium ionophore A23187 or electric pulsation and 6-DMAP, and cultured for 6 days. As for the oocytes collection methods, activation treatment in the presence of cytochalasin B did not affect the developmental rate of embryos reconstituted with 44-h-mature recipients. However, the development rate of reconstituted embryos with 33-h-mature recipients was significantly higher(p < 0.05) by activation with the combination of electric pulsation and 6-DMAP. These results suggest that reconstituted porcine embryos derived from cultured cumulus cells can develop to the blastocyst stage and that the development of the former could be improved by reconstruction with young oocyte cytoplast after the activation with the combination of electric pulsation and 6-DMAP.