Comparison of in vitro development and gene expression of in vivo- and IVM/IVF-derived porcine embryos after microinjection of foreign DNA

We compared the developmental ability and gene expression of in vivo- and IVM/IVF-derived porcine embryos following microinjection with SV40-LacZ. A total of 412 IVM/IVF-derived and 129 in vivo-collected zygotes was used to examine developmental ability and gene expression following DNA microinjection. When either DNA injected or noninjected zygotes were cultured for 4 d in NCSU 23 followed by 5 d in Eagle's minimal essential medium (EMEM), the percentages of zygotes developing to blastocysts and hatched blastocysts were higher (P < 0.05) compared with groups cultured in NCSU 23 alone. The percentages of injected embryos reaching the morula and blastocyst stages were significantly lower (P < 0.05) than that of noninjected control embryos whether in vivo or IVM/IVF derived. The percentages of morula and blastocyst stage embryos expressing the gene were higher in the in vivo-derived embryos than in IVM/IVF-derived embryos. A lower proportion of (67 to 77%) mosaicism was observed in the in vivo-derived embryos than in IVM/IVF (90 to 100%) derived embryos. The total cell number of blastocysts cultured in both NCSU 23 and EMEM media was significantly higher than that of blastocysts cultured continuously in NCSU 23. Our results suggest that this dual culture system enhanced embryo viability following microinjection of foreign DNA.