Abstract: Through epididymal transport, sperm undergo a series of biochemical and morphological changes and gradually acquire maturation. During the process of sperm maturation, most of its cytoplasmic components are lost, sperm are more sensitive to oxidative stress, which lead to the damage of sperm structure and function. Therefore, the role of antioxidant enzymes in the epididymal cavity microenvironment is very important. Reactive oxygen species(ROS) play a dual role in sperm function:Physiological levels of ROS can promote the pre-fertilization capacitation of sperm, while high levels of ROS can lead to oxidative damage of sperm. Antioxidant enzymes that remove excess ROS from the epididymis include superoxide dismutase(SOD), catalase(CAT), glutathione peroxidase(GPXs) and peroxidase(PRDXs), however, the contents of different antioxidant enzymes in epididymis varied with the parts of epididymis and animal ages, and different antioxidant enzymes have different scavenging mechanisms to ROS. When the epididymis lacks a certain antioxidant enzyme, the sperm DNA is damaged, the sperm quality is reduced, and eventually leads to increased abnormal reproductive outcomes. Obviously antioxidant enzymes in mammalian epididymis need to coordinate with each other to maintain ROS at physiological level, however there are few reports on this topic at present. The antioxidant enzymes secreted by epididymal epithelial cells are transported to sperm in the form of epididymosome, which can eliminate ROS produced by their own aerobic metabolism and abnormal sperm, and ensure the normal maturation of sperm. This paper reviewed the oxidative stress of epididymal sperm and the protective effect of various antioxidant enzymes in epididymis on sperm.

Key words: epididymis; sperm; antioxidant enzymes; reactive oxygen species; oxidative stress