cool dude... u have asked the good question the CRYPTROCHIDISM......actually the development of testis occurs in the abdominal cavity. but during the seventh month of the foetal life the testes descend into the scrotal sac due to the presence of testosterone hormone .so the testis in man is extra abdominal.but when it fails to descend then it is called cryptrochydism. . .

Failure of testes to descend into the scrotum (supposed to happen in the 7th month of pregnancy) is cryptorchidism. It is corrected by surgery.

When boy is in his mothers woumb his testis are in his abdomen during birth this testis by inguinal canal comes to scrotum if it does not come down it is called crypdorchiism