Vas deferens

The vasa deferentia (singular vas deferens) are a pair of tubes in the male reproductive system that carry sperm from the epididymus in the testicles to the ejaculatory ducts where they are mixed with semen and stored.
A sterilization procedure, the vasectomy, severs the vasa deferentia, preventing sperm from reaching the ejaculatory ducts without affecting either semen or potency.
Vas deferens at Wikipedia
Category:Anatomy