In vasectomy, Vas deferens short segment is cut and tied. Structure of male genital organ is : 1.. Testes- Spermatogensis occur. 2. Vas efferentia- Pierce the testes and enter into head of epididymis. 3. Epididymis- Sperm enter into head of itand stored into tail of it.It opens into vas deferens. So, sperms first enter into epididymis then into vas deferens,through vas deferens it won't further enter into Ejaculatory duct as vas deferens has been cut.