sciencehabit writes: How the male body produces sperm has long been hidden inside its genitalia. Trying to recreate the process in a lab for humans and other mammals has led to many failures - sperm development appeared to be dependent on unique conditions in the testes. But a new technique may finally be bringing that process into the open. A team of Chinese researchers reports turning a dish of a certain type of mouse stem cell into spermlike cells, which were then used to fertilize eggs and produce healthy mouse pups. The approach could help researchers study mammalian sperm development more directly, and it could spur efforts to develop treatments for male infertility in people.