Abstract: To investigate the roles of mitochondrial oxidative phosphorylation (OXPHOS) capacity in oocyte maturation, fertilization and embryo development. Methods: Carbonyl cyanide p- (tri-fluromethoxy) phenyl-hydrazone (FCCP), a metabolic inhibitor of mitochondria, was introduced into culture medium. The integrity of spindle and chromosome alignment, reactive oxygen species (ROS) levels, and rates of maturation, germinal vesicle breakdown, fertilization and blastulation were assessed in vitro. Results: Significant decreases were detected in the percentages of oocytes with nuclear maturation, normal spindle formation and chromosome alignment, ROS levels and capable for blastocyst formation between oocytes treated with FCCP and non-treated (control group), 55.8%, 37.9%, 0.67 and 57.9% (FCCP 10 nmol/L group), 47.3%,34.7%, 0.59 and 41.8% (FCCP 100 nmol/L group) versus 62.9%, 61.9%,0.94 and 68.3% (control group) respectively, P < 0.05. However, No significant differences were found in the rates of GVBD and fertilization in oocytes from the FCCP treated and the control. Conclusion: Inhibition of mitochondrial metabolic capacity resulted in decreased the percentages of oocytes with nuclear maturation, normal spindle formation and chromosome alignment, ROS levels and capable for blastocyst formation. But the treatment of FCCP did not affect the rate of fertilization.

Key words: Mitochondria, Oxidative phosphorylation, Oocytes, Fertilization in vitro