The urethra of the male has a duel purpose, it is a tube that passes through the prostrate gland, then through the urogenital diphragm, and finally the penis. it expels the waist (urine) from he bladder to the outside, and it also transports ejaculate, during the act of reproduction, while the act of reproduction is being carried out and the penis is erect the flow of urine will be blocked, so it cannot enter the urethra this allows only the semen to be ejaculated during reproduction.
(information, n.d.)
(Tortora & Grabowski, Reynolds, 1996)
Vas deferens - it ascends along the posterior border of the epididymis, it penetrated the inguinal canal and enters the pelvic cavity, it then loops the ureter and over the side and down the posterior surface of the bladder, the function of he Vas deferens is to pass sperm by peristaltic contractions from the epididymis to the urethra, it is a long tube about 45cm in the human but again this will be different in alternate species, and has a three layers of muscle, the Vas deferens can also be a storage chamber for the sperm they can remain viable with in the vas deferens for up to 7 months (but at very low metabolic rates) (Tortora & Grabowski, Reynolds, 1996)