Cryptorchidism Cryptorchidism is distinct from monorchism, the condition of having only one testicle. Though the condition may occur on one or both sides, it more commonly affects the right testis. A testis absent from the normal scrotal position may be: About two-thirds of cases without other abnormalities are unilateral; most of the other third involve both testes. In 90% of cases, an undescended testis can be felt in the inguinal canal. In a small minority of cases, missing testes may be found in the abdomen or appear to be nonexistent (truly "hidden"). Undescended testes are associated with reduced fertility, increased risk
Scrotum upon the ambient temperature. This is accomplished by the cremaster muscle in the abdomen and the dartos fascia (muscular tissue under the skin). Having the scrotum and testicles situated outside the abdominal cavity may provide additional advantages. The external scrotum is not affected by abdominal pressure. This may prevent the emptying of the testes before the sperm were matured sufficiently for fertilization. Another advantage is it protects the testes from jolts and compressions associated with an active lifestyle. Animals that move at a steady pace – such as elephants, whales, and marsupial moles – have internal testes and no scrotum.