Figure 3.

A summary of some of the factors contributing to oxidative stress in human spermatozoa. The major sources of ROS include disturbed electron flow in the sperm mitochondria, enhanced amino acid oxidase activity, or an increase in ROS generation by NADPH oxidases such as NOX5. Some of the drivers for enhanced ROS generation via these pathways are highlighted. Oxidative stress can also arise because of deficiencies in antioxidant protection due to impaired intake in the diet, or high levels of antioxidant turnover/consumption due to chronic ROS generation, associated with conditions such as obesity, varicocele, and the detoxification of environmental toxicants.