The ejaculatory ducts are a part of the male anatomy that allows the flow of sperm from the testes through the reproductive system and eventually out through the urethra.
After sperm are created in the testes and matured in the epididymis, the event of ejaculation moves sperm through the epididymis and into the vas deferens via smooth muscle contractions. Each testicle has a separate vas deferens, which move up out of the scrotum and into the body, joining together to create the beginning of the ejaculatory ducts.
After leaving the vas deferens, sperm from the testes and epididymis move through the ejaculatory ducts and mix with emissions from the prostate gland and seminal vesicles. Further muscle contractions push these emissions out of the prostatic structures and prepare it for expulsion. These emissions nourish sperm, keeping them active and motile, as well as protect them in the acidic vaginal environment.
After these emissions and sperm mix together, they become ejaculate. Upon the expulsion stage of ejaculation, this ejaculate exits the ejaculatory ducts, and enters the urethra, the last physiological structure before muscle contractions propel the ejaculatory mixture from the body.