In the United States, an estimated 645,000 men ages 20 to 50 have azoospermia, a condition in which no sperm are present in their ejaculate. Now, scientists are testing a potential treatment: ...

A man in his early 20s received a transplant of his own sperm-producing stem cells, which had been frozen since his childhood, in an attempt to regain fertility. Doctors are waiting to see if the ...