Side View of the Prostate
The prostate is a walnut-sized gland located between the bladder and the penis. The prostate is just in front of the rectum. The urethra runs through the center of the prostate, from the bladder to the penis, letting urine flow out of the body.

The prostate secretes fluid that nourishes and protects sperm. During ejaculation, the prostate squeezes this fluid into the urethra, and it's expelled with sperm as semen.

The vasa deferentia (singular: vas deferens) bring sperm from the testes to the seminal vesicles. The seminal vesicles contribute fluid to semen during ejaculation.