Apoptosis of mouse embryos of different developmental stages in the untreated control and the treated groups.

Data are presented as mean±SD, hpi: hours post insemination. The apoptotic rate for each embryo was expressed as the percentage of apoptotic cell number relative to the total number of the embryo. Embryos fertilized with hydrogen peroxide-stressed sperm were defined as the treated group, and those fertilized with fresh sperm were defined as the untreated control group.*p>0.05, the treated group vs. the untreated control group, Chi square test was use to compare the composition difference of apoptotic cell number of the two groups.