Oxidative Stress in Oocytes and Embryo Development: Implications for In Vitro Systems

To improve the outcomes of in vitro culture of human oocytes and embryos, the dynamic balance and roles of reactive oxygen species (ROS) in folliculogenesis and embryo development merit further consideration. ROS have been demonstrated to participate in various signaling processes and act as mediators in various physiological events in germ cells. An imbalance between pro-oxidants and antioxidants seems to explain the high failure rate of assisted reproduction. Oxidative stress induced by excessive ROS or insufficient antioxidant protection can cause detrimental effects on both male and female reproduction. In this study, oxidative stress in folliculogenesis and embryo development are summarized and the multiple modifiable factors of in vitro culture systems in relation to ROS are discussed. More studies are needed to establish an optimal redox state in in vitro culture systems for human oocytes and embryos.