What do the male sex organs do?

The external male sex organs include the penis and the scrotum. Each penis looks a little different, for instance in its length or thickness.

The penis is made up of the root of the penis, the shaft, and the round glans (head) at the tip of the penis. The glans is covered with a mucous membrane. The movable foreskin covers the head of the penis. Some men have had the foreskin cut off (circumcised) in a surgical procedure that shortens the foreskin or removes it completely. This maybe done if the foreskin is too tight, for example.

A tube called the urethra runs through the inside of the penis. Urine leaves the body through the urethra, and so does semen (the fluid that carries sperm) during ejaculation.

The shaft and the head of the penis contain erectile tissues called corpora cavernosa. These tissues are like sponges. During sexual arousal, blood builds up in the corpora cavernosa until they are full and firm. This allows the penis to become erect and stiff (erection). In most men, it also becomes longer and thicker. The penis can then be put into the vagina during sex between a man and a woman so that an egg cell can be fertilized after ejaculation.

The scrotum is a bag of skin that surrounds the testicles and the epididymis. The vas deferens tubes (sperm ducts) are also connected to the epididymis.

The head of the penis and the skin on the penis, scrotum and the surrounding area contain a dense network of nerve fibers. This makes the external sex organs very sensitive. As a result, touching and rubbing this area can cause sexual arousal and increased pleasure that may lead to orgasm and trigger ejaculation.

The main internal male sex organs include:

• Testicles
• Epididymis
• Vas deferens tubes
• Seminal vesicles
• Prostate

The two roundish, egg-shaped testicles produce the male sex hormone testosterone, which influences various processes inside the body, and during puberty controls the development of a child's body to an adult male body. Testosterone also plays a role in the development of sexual desire. The testicles also make sperm cells. Only these cells are capable of fertilizing an egg cell. They start to develop inside the abdominal cavity of a male embryo. As the embryo grows, they drop down out of the abdominal cavity and into the scrotum through the inguinal canals.

A worm-shaped epididymis is attached to each testicle. The epididymis takes the sperm cells from the testicles and allows them to mature into sperm that can move. The mature sperm are stored in the epididymis until the next ejaculation.

Both of the thin vas deferens tubes lead from the epididymis to the prostate. There they join the urethra tube, through which sperm can leave the body. Just before the vas deferens tubes reach the urethra, they pass by the seminal vesicles. The seminal vesicles produce a fluid that mixes with the sperm cells to form semen. One part of the semen is produced by smaller glands near the base of the urethra and in the prostate. During ejaculation, the muscles in the pelvic floor contract. This causes the semen to be squirted out of the urethra. The released semen is called ejaculate (or "come").

The female and male sex organs develop in an embryo from the more basic structures during the first few months. Genes and hormones determine how they grow. The gonads then develop either into ovaries or testicles. Another tissue then forms the clitoris or the penis, which explains their similar structure. Sometimes the sex organs develop in a way that is neither clearly male nor clearly female. This is called intersex.

In addition to the internal and external sex organs, there are also secondary sex characteristics. They do not develop until puberty.

The secondary male sex characteristics mainly include increased body hair on the chest, belly and back and in the armpits and genital region, as well as the growth of facial hair. There is also a “breaking” of the voice during puberty, making the voice lower.