Welcome to mating 2.0: the sexual act itself might not change, but when the parts don't work, we'll simply build new ones.

Cell

So say scientists in Japan who, using stem-cell techniques, are the first to engineer sperm in infertile male mice that successfully fertilized eggs and produced offspring.

The team, led by Mitinori Saitou at Kyoto University, report in the journal Cell that it used stem cells to create primordial germ cells, the precursor to sperm cells, and injected those germ cells into the testicles of infertile mice. The cells eventually produced normal-looking sperm, which went on to fertilize eggs and produce healthy--and perhaps most notably, fertile--offspring.

Scientists have already tried to create sperm using stem cells in previous in vitro studies and, as with this study, used both mice and human stem cells. But until now they hadn't had success.

Whether this recent achievement will eventually translate into human fertility advances remains to be seen, but the team plans to study these and future generations of mice closely, and its findings will likely prompt more research into the biological nature of primordial germ cells.

Not a combination of words I'd recommend in a pick-up line.