Following male orgasm, sperm are ejaculated after traveling rapidly in
sequence through the vas deferens duct, the prostate gland, and the
urethra. The vas deferens must be patent to allow the passage of sperm
in the ejaculate.

CAUSES OF TOTAL OBSTRUCTION OF THE VAS DEFERENS: 

* _Primary occlusion: Congenital (Bilateral) Absence of the Vas
Deferens (CBAVD):   _In some cases men are born with occlusion of
the vas deferens, obstructing the…