Males in whom tests fail to descend to the scrotum are generally infertile why ?

Males in whom testes fail to descend to the scrotum are generally infertile. Why?

Males in whom testes fail to descend to the scrotum are generally infertile. Why?

Males in whom testes fail to descend to the scrotum are generally infertile. Why ?

Males in whom testes fail to descend to the scrotum are generally infertile. Why?

Males in whom testes fail to descend to the scrotum are generally infertile. Why?

Males in whom testes fail to descent to the scrotum are generally infertile. Why?

Express in one or two word(s) Males whose testes fail to descend to the scrotum are generally infertile, why?