All of the following are paired structures of male reproductive system, except

Testes, vas deferens and seminal vesicles are paired structures. The ejaculatory ducts are paired structures in male anatomy. 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 open into the urethra. Urethra is single duct that helps in passage of semen as well as urine in males.