Sperm after leaving the nucleus are not yet fully mature. In the epididymis undergo a series of morphological changes , biochemical and functional . Their effect is to achieve the ability of sperm to the progressive movement , survival in male and female genital tract , capacitation , acrosome reaction and carrying out fertilization of the ovum . The specific environment in which the spermatozoa mature and are maintained viability , is produced by the epithelial cells lining the duct of the epididymis .