Abstract
Nuclear-transferred mouse eggs receiving embryonic stem cells develop into blastocysts at a high rate, but their potential to develop into fetuses is very low. Therefore, the present study examined the effects of aggregating of two nuclear-transferred eggs at the 8-cell stage to increase the cell number of nuclear-transferred embryos. The proportion of implantation sites on gestational day 10.5 after transfer of aggregated nuclear-transferred embryos (53%) was significantly higher than after single nuclear transfer (29%) or serial nuclear-transfer (37%). The proportion of implantation sites with fetuses did not differ significantly among the three groups (7 to 17%). These results demonstrate that the low potential of nuclear-transferred embryos with embryonic stem cells to develop into fetuses is not due to the lower cell number of nuclear-transferred embryos.
