Effects of Low Oxygen Condition on the Generation of Reactive Oxygen Species and the Development in Mouse Embryos Cultured in vitro*

OBJECTIVE(S): To elucidate the relationship between intracellular H2O2 production and embryo development in different oxygen culture conditions. METHODS: Pronuclear stage embryos were obtained from C57BL/CBA F1 and ICR mice. Measurement of H2O2 level was performed with 2',7'-dichlorodihydroflourescein diacetate and the number of blastomeres was counted after staining with 4',6'-diamidino-2-phenylindole. RESULTS: Regardless of strains, H2O2 level reached a peak at the 2-cell stage in 20% O2. But in embryos cultured in 5% O2 it was significantly lower at the 2-cell and 4-cell stages compared to those from 20% O2. The embryos cultured in 20% O2 showed developmental delay or block, but in 5% O2 these phenomena were overcome and the development was significantly increased with an infrequent fragmentation. CONCLUSIONS: Our data suggest that the 5% O2 decreases the relative concentration of H2O2 and results in improved embryo development in terms of quantity and quality without regard to type of strains.