Male sexual and reproductive organs

The penis and testicles

The penis is partly inside and partly outside the body. It’s made up of several types of tissue. These include skin, muscle, blood vessels and nerves. Inside the penis is the urethra. Urine and semen flow through this tube and eventually pass out of the small slit at the end of the penis (the meatus).

The end of the penis is also known as the head of the penis (glans). It's normally covered by a piece of skin called the foreskin (prepuce). But some men may have had the foreskin removed during an operation called a circumcision. This operation is usually done at birth but may be done later in life.

For most men the ridge below the head of the penis (the frenulum) is the most sensitive part of their penis. The penis has a rich blood supply, as well as a muscle layer and nerves. When sexually aroused the blood flow increases and the penis becomes erect.

The scrotum is the pouch of skin that hangs below the penis and holds both testicles (testes). The testicles are part of the male reproductive system.

From the age of puberty the testicles produce sperm, which can fertilise a female egg. Next to each testicle is the epididymis, a tube where sperm is stored. The testicles produce the male sex hormone, testosterone.

The prostate gland

The prostate is a small gland about the size of a walnut. It surrounds the top part of the tube that carries urine from the bladder to the penis (the urethra). The same tube also carries semen. The prostate produces a thick clear fluid, which is an important part of the semen.

The growth and function of the prostate gland depends on the male sex hormone testosterone, which is produced in the testes.

Male sex hormones

Testosterone is the main male sex hormone. It is made in the testicles. Testosterone is the main cause of male qualities such as:

• a deep voice

• body hair growth

• muscle development

• the ability to have an erection

• sex drive (libido)

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