Friday 30 January, 2009It's not the end of men—it's a future with more fathers!

For the first time, scientists have turned embryonic stem cells—which can be grown into any cell type—into sperm that are capable of generating offspring. The breakthrough could lead to advances in treating male infertility, one day helping childless couples to make their own babies. Even lesbian couples.

Researchers at Newcastle University in England demonstrated that embryonic stem (ES) cells from a mouse could be developed into mature sperm in the laboratory or could be transplanted into the testes of mice, where they could still develop into sperm.

The ES-derived sperm were injected into mouse eggs, and the fertilized eggs grew into early-stage embryos that were successfully transplanted into mice. Seven mice were born, and six of them grew into adulthood. True, all the mice had health problems of the kind commonly seen in cloning experiments—trouble walking, for instance, or obesity. A lot more study remains to be done.

But for childless couples of all species and sexual persuasions, a more fruitful future seems to be one step closer.