Notes

Testes The testes (testicles) (singular, testis) are the male repro- ductive organs that make sperm and testosterone. At puberty and throughout a male's life, the testes produce several hun- continuing dred million sperm each day. The sperm are made inside the testes in tightly coiled tubules called seminiferous tubules. Testosterone is the major sex hormone of males. During puberty testosterone causes facial and body hair to grow, the shoulders to broaden, and the voice to deepen. Testosterone also influences sperm production. The two testes rest in the scrotum, a skin-covered sac that hangs from the body. The small muscles in the scrotum move the testes doser or farther from the body This movement keeps the sperm a little cooler than normal body temperature. Sperm cannot develop properly at the higher temperatures of the inner body Penis The penis is the male reproductive organ that removes urine from the male's body and that can deliver sperm to the female repro- ductive system. The penis is made of soft tissue and blood vessels. During sexual activity, the penis becomes erect, or firm. The erection occurs as the blood vessels in the penis fill with blood. The penis must be erect during ejaculation (ee JAK yoo LAY shuhn). Bjaculation occurs when sperm are released from the penis after sexual excite- ment. It is also normal for males to ejaculate while they are sleeping These ejaculations are called noctumal emissions or "wet dreams.