Abstract:

Reconstructed embryos can be got by two nuclear transfer methods, fusion and microinjection. However, the fusion method is time-taking and has low efficiency. Microinjection involved the donor nucleus isolation, which may lead to the damage of the nucleus DNA. Cloning efficiency may be reduced by low fusion rate of the cell fusion method and damaged DNA of microinjection method. So some researchers used the intracytoplasmic injection of the whole-cell donor, which was simple and less labor-intensive for cloning study. Here we used the intact cumulus cell as donor to study the feasibility of the microinjection method in mouse nuclear transfer. After the whole cell injection of the cumulus, most of the couplets were fragmented following activation at 1 or 6 h after injection. Whereas those only the nucleus after isolation from the cumulus was injected cleaved and developed normally. The control group of oocytes, which were not injected with the donor, was also fragmented after enucleation. Most of the couplets of the parthenotes after intact cumulus cell injection were fragmented. The group of those in which the donor was just broken and then injected (nucleus with

most of the broken membrane and the cytoplasm were injected) developed as a lower rate compared to those only isolated nucleus being injected. These results suggest that the intact donor membrane of cumulus cell hinder the re-programming of oocyte for somatic nucleus and components of donor cytoplasm and membrane affected the devel-opment of the clones in vitro.