Highly read on www.cell.com in August

Mouse stem cells can be transformed into reproductive tissue able to churn out sperm.

Mitinori Saitou and his colleagues at Kyoto University in Japan coaxed embryonic stem cells into forming a type of cell called an epiblast, which is found in developing embryos. Reprogrammed stem cells were also able to do this. Subsequent treatment of these epiblasts with a cocktail of proteins and nutrients converted them into the germ cells that make sperm.

The authors implanted these cells into the testes of mice lacking their own germ cells. After 10 weeks, the testes of some of the animals generated sperm, which, in turn, fertilized eggs to create healthy male and female mice. A similar approach with females might provide a renewable source of egg cells.

Cell 146, 519–532 (2011)