Effect of polyethylene glycol and dimethyl sulfoxide on the fusion of bovine nuclear transfer using mammary gland epithelial cells.

The effects of polyethylene glycol and dimethyl sulfoxide (PEG/DMSO) treatment of donor cells on the fusion and subsequent development of bovine nuclear transfer embryos using mammary gland epithelial (MGE) cells before electrofusion (fresh MGE cells) was studied. The same study was conducted on those cells that were frozen and stored in liquid nitrogen, and then thawed (frozen-thawed MGE cells). Experiment 1 showed that the exposure time and pH of PEG/DMSO solution affected the fusion of nuclear transfer, and that a higher fusion rate was obtained when fresh MGE cells were exposed to PEG/DMSO solution at pH 8.0 for 5 min. In Experiment 2, the proportion of fused oocytes with fresh PEG/DMSO-treated cells (70 ± 6%) was significantly higher than that with non-treated cells (50 ± 13%, p < 0.05). The same tendency was observed when frozen-thawed cells as donor nuclei were used (48 ± 6% vs. 34 ± 12%, p < 0.05). In addition, PEG/DMSO treatment has neither harmful nor beneficial effects on the cleavage and devel...