(Read 'History Of Vasectomy') To better understand why a vasectomy makes you unable to have children, (see illustration of the male reproductive system) It is important to understand some of the anatomy of this system. Sperm are produced in each testicle within the scrotum and are stored in the epididymis (a small “bag” that sits on top of the testicle). When called for, the sperm move up the vas deferens (the “sperm tube”) of each testicle to the urethra (“urine tube”) of the Penis. Along the way, the seminal vesicles and the prostate gland secrete fluids that nourish and transport the sperm. When you have an orgasm, you ejaculate semen which is 98% sperm nourishment fluid and 2% sperm. During a vasectomy, each vas deferens is blocked so that the sperm cannot travel though it. Usually a piece of each vas is removed and the cut ends are sealed.