Japanese scientists have successfully made sperm from stems cells, called iPS cells.  Note only that but they have a bunch of baby mice to show for it.

The iPS cells were mixed with a protein, which turned the iPS cells into primordial cells that can develop into sperm.

Don’t worry men, you’re still involved.  The primordial cells are then injected into the male’s testis, where they develop into sperm.  The experiment worked with mice.  It’s hoped this process could help men who can’t develop their own sperm.