Say: un-DIH-sen-did TESS-tih-kul
A testicle is an egg-shaped gland that makes and holds sperm. There are two of them in the sac called the scrotum (say: SKROH-tum) that hangs underneath a boy's penis. When a baby is developing inside his mom, his testicles grow in his abdomen and then drop, or descend, into the scrotum.
Undescended testicle is a condition in which one or both of a boy's testicles have not moved into their proper place in the scrotum. The testicle may move down on its own within a few months. If it doesn't, the doctor will do surgery to move it.