High level of intracellular sperm oxidative stress negatively influences embryo pronuclear formation after intracytoplasmic sperm injection treatment

Summary This study evaluates the relationship between sperm intracellular reactive oxygen species ( ROS ; H 2 O 2 , O 2 ), DNA fragmentation ( DF ), low mitochondria membrane potential ( MMP ) of sperm and normal pronuclear formation among intracytoplasmic sperm injection ( ICSI ) patients. Semen samples were obtained from 62 infertile male who were candidates for ICSI treatment. After sperm processing, metaphase II ( MII ) oocytes were injected, and the mean percentages of intracellular ROS , MMP and DF were evaluated using flow cytometry. The mean percentages of pronuclear formation and zygote score ( Z ) were also recorded, and Pearson, Spearman's rank correlation coefficient and Kruskal–Wallis tests were applied to analyse the data. The amounts of sperm intracellular H 2 O 2 and O 2 − ˙ had significant positive correlation with low MMP ( P  <   0.01). The intracellular ROS had a negative correlation with pronuclear formation ( P  <   0.05), and its effect was higher than 66.66%. In addition, the mean percentages of neither H 2 O 2 nor O 2 − ˙ affected the quality of pronuclear embryos ( Z ‐score). This study shows that although high levels of both sperm intracellular H 2 O 2 and O 2 − ˙ in ICSI patients have deleterious effect on sperm MMP , only H 2 O 2 may interfere in pronuclear formation.