In vitro Development of Chimeric Bovine Embryos Created by Combining a Single Blastomere of SCNT Embryos with an IVF Embryo

In this study, we produced chimeric embryos from a single blastomere of somatic cell nuclear transfer (SCNT) bovine embryo and in-vitro fertilized (IVF) bovine embryo, and examined the rate of blastocyst development and the contribution of the SCNT blastomere to the blastocyst in order to improve cloning efficiency. We produced SCNT embryos from bovine fibroblasts carrying a luciferase gene under the control of the β-actin promoter. At 96 hours post fusion, chimeric embryos were produced by transferring a single blastomere of a 16-cell SCNT embryo to the perivitelline space of an IVF embryo. At 4 days after production of the chimeric embryos, half of the embryos reached the blastocyst stage, which is the same as that of IVF embryos. Furthermore, luciferase activity in blastocysts from the chimeric embryos was detected in both the inner cell mass and trophectoderm. These results indicate that single blastomeres of SCNT embryos contributed to both the inner cell mass and trophectoderm in blastocysts from chimeric embryos.