Inside a man's body, the testicles make tiny cells called sperm, which are needed for sexual reproduction. The testicles also make a hormone called testosterone. This is a chemical that makes a person grow into a man and feel like a man. The testicles are glands, which are special parts of the body that make chemicals. Other glands that make up the genitals are the prostate, seminal vesicles and bulbourethral glands (also called the Cowper's glands). Together, these glands make a white, sticky fluid called semen that sperm float in. Finally, a man's body contains ducts (tubes) such as the two vasa deferentia or ducta deferentia, which carry sperm out of the testicles; and the urethra, which carries semen through the penis and out of the body. The urethra also carries urine away from the bladder.