The seminal vesicles are two sac-shaped structures that produce part of the thick fluid (semen) that contains sperm. The vesicles are located just above the prostate gland.

The seminal vesicles join with the vas deferens to become the ejaculatory duct. This duct enters the urethra. During ejaculation, this duct allows semen to travel through the tube (urethra) that leads outside the body through the penis.