抄録
An attempt was made to use the zygotes arrested at the M phase of the cell cycle as the recipient cytoplasm for nuclear transfer. i) Zygotes which were collected 24, 28 and 32 h after hCG injection were incubated in M16 + nocodazole (3 μl/ml) for 10 to 14 h. After elimination of the drug, they were cultured in vitro for 4 days. ii) Blastocysts were cultured with nocodazole for 5 to 12 h and the mitotic index was examined. iii)M phase and G1/S phase inner cell mass (ICM) cells synchronized with nocodazole and aphidicolin treatment, and fetal germ cells isolated from fetuses on days 11.5 (in mitosis) and 15.5 (G0 phase) of pregnancy were fused with enucleated M phase zygotes. The results were as follows. i) Zygotes obtained 24 h after hCG injection and treated with nocodazole for 10 to 14 h were at the M phase. After release from the drug, they developed to blastocysts at a rate similar to that of non-treated zygotes (83∼87% vs 100%). ii) Mitotic index of blastocysts treated with nocodazole for 11 to 12 h was 94%. iii) Nuclear transfer into M phase zygotes did not improve the developmental ability of reconstituted embryos into blastocysts. In the present study, it was clear that mouse zygotes arrested at the M phase with nocodazole treatment, and after washing they developed to the blastocysts at the similar rate to non-treated zygotes. But, the developmental ability of reconstituted zygotes at the M phase did not support in vitro development.
