The epididymis is a duct located along the posterior surface of each testis. The vasa efferentia, which transport sperm from the testis, open into the epididymis. The epididymis then leads to the vas deferens which ascends to the abdomen and loops over the urinary bladder. The main function of the epididymis is to store and transport sperms from the testis to the outside through the urethra.