The Ejaculatory ducts (ductus ejaculatorii) are paired structures in male anatomy, about 2 cm in length. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and empty into the urethra at the Colliculus seminalis. During ejaculation, semen passes through the ducts and exits the body via the penis[WP,unvetted]. [ http://en.wikipedia.org/wiki/Ejaculatory_duct ]