* The testicles are two small round organs covered with skin that are located under the penis. Each testicle is connected to the penis by a tube through which the sperm travel.

When a boy reaches puberty, the testicles start to produce millions of sperm.

* The penis is cylindrical in shape, and contains a tube called the urethra.

Both the sperm and urine leave the body through the urethra in the penis.

There is a valve where the bladder and the urethra meet that prevents the urine and sperm from mixing.

Front view

Side view