Prostate gland. Computer artwork of part of the male urogenital system, rear view. The prostate gland (pink) sits below the bladder (round, orange), surrounding the urethra (not seen), the duct that carries urine and semen out of the penis. At top left and right, ureters (orange tubes) carry urine from the kidneys to the bladder. Semen is a mixture of sperm (produced by the testicles, not seen) and secretions from the prostate and seminal vesicles (short yellow tubes, lower centre). The sperm reach the prostate through one of the two vas deferens tubes (yellow, looping around ureters).