1.The epididymis is the site of sperm maturation, and a decrease in the secretion function of the epididymis will have an adverse effect on the vitality and function of spermatozoa. Seminal plasma neutral alpha-glucosidase combined with seminal plasma fructose assay can localize the site of obstruction in patients with obstructive azoospermia, which greatly improves the value of non-invasive diagnosis of obstructive azoospermia.