This difference in requirements regarding O2 tension suggests that there are differences in the metabolism of these embryos. Previous studies show that SCNT embryos grow better in a low O2 environment. which is consistent with O2 consumption in SCNT embryos. Another study, in mice, also indicated that SCNTembryos have different culture requirements as compared to IVF- or in vivo-produced embryos, as SCNT embryos developed better in somatic cell media than in embryo
culture media. The author suggested that somatic cell-like features still remain in SCNT embryos. Thus, SCNT embryos may develop via a different metabolism than IVF embryos.