In mammals, the primary male sex organs, testes are located in the extra-abdominal scrotal sacs. Scrotum maintains a low temperature of $2 - 4℃$ below the temperature of abdominal cavity. As higher abdominal temperature kills the spermatogenic tissue So, testes in mammals are contained scrotal sacs present outside the abdominal cavity to have the low temperature that is needed for the formation and maturation of functional sperms.