From Boy to Man: Male Reproduction When a baby boy is born, he has all the parts of his reproductive system in place, but it isn't until puberty that he is able to reproduce.
Scrotum The scrotum is a thin, but muscular, sac of skin that hangs below the boy’s body. This sac of skin helps to regulate the temperature of testicles, which need to be kept several degrees cooler than body temperature to produce sperm.
Testicles and Testosterone Inside the scrotum, are the two testicles, also called testes, which produce the millions of tiny sperm cells. The testicles also produce hormones, including testosterone.
Seminiferous Tubules Sperm develop in the testicles within a system of tiny tubes called the seminiferous tubules. These tubules contain simple round cells that transform into sperm cells during puberty.
Sperm Cell A male who has reached puberty will produce millions of sperm cells every day. Each sperm is extremely small: only 1/600 of an inch.
Knowledge Check Q: What is the main function of the scrotum? A: to regulate the temperature of the testes Q: What is produced in the testes? A: sperm and hormones Q: What are the seminiferous tubules? A: the coiled network on tubules inside the testes
Epididymis The sperm complete their development in the epididymis, which is a comma-shaped structure that sits along the upper back side of each testicle. It takes sperm about 4 to 6 weeks to travel through the epididymis while it matures.
Vas Deferens Once the sperm mature, the vas deferens, a muscular tube, carries the sperm from the epididymis up to the ejaculatory duct where it will be mixed with fluids and released from the body.
Ejaculatory Duct The ejaculatory duct is a short, straight tube that is formed by the vas deferens tube and the seminal vesicle and leads into the prostate gland. This is where the sperm will wait to be ejaculated from the body.
Knowledge Check Q: Why do the sperm stay in the epididymis? A: to complete their development Q: What is the function of the vas deferens? A: to carry sperm from the epididymis to the ejaculatory duct Q: What happens to the sperm in the ejaculatory duct? A: they wait to be ejaculated
Semen There are several glands that provide fluids that mix with the sperm and help it to move through the system. This mixture of sperm cells and fluids is called semen.
Seminal Vesicles The seminal vesicles are sac-like structures attached to the vas deferens. They add a sugary fluid that nourishes the sperm cells and gives them energy.
Prostate Gland The prostate gland surrounds the ejaculatory duct just below the bladder. It releases a chemical alkaline fluid into the urethra to neutralize the acids that are left behind in the urethra after a male urinates. The prostate gland is also a common site of cancer in older males.
Cowper’s Glands Beneath the prostate gland is a small, pea-sized gland called the cowper’s gland. It releases a lubricating fluid that helps give the sperm more mobility. It is also called a pre-ejaculatory fluid and is present during an erection. This fluid can contain thousands of sperm cells that could get a female pregnant even if the male does not ejaculate.
Knowledge Check Q: What is the mixture of sperm and fluids called? A: semen Q: What is the purpose of the sugary fluid? A: to give energy to the sperm Q: What is the purpose of the prostate fluid? A: to neutralize acid in the urethra
Urethra The urethra is the tube that extends from the bladder to the outside of the body through the penis and is a passageway for both urine and semen. While a male can urinate and ejaculate, he cannot do them both at the same time.
Penis The penis is made of a spongy erectile tissue that can expand and contract. It is the male reproductive organ used during sexual intercourse, but also functions in urination.
Foreskin The fold of skin at the end of the penis covering the glans is known as foreskin. The removal of the skin is called circumcision
Erection The inside of the penis is made of a spongy erectile tissue that can expand and contract. An erections is when the tissue in the penis fills with blood and it becomes stiff and hard.
Ejaculation When muscles around the reproductive organs contract and force the semen out of the male's body through his urethra — this process is called ejaculation. Each time a male ejaculates, it can contain up to 500 million sperm.
Knowledge Check Q: What is the function of the urethra? A: it is a passageway for urine and semen Q: What term describes the removal of foreskin? A: circumcision
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