Researchers claim to have made artificial mouse sperm in a dish

Researchers in China say that they have discovered a way to make rudimentary mouse sperm in a dish, and used them to produce offspring.

If the claim stands up to scrutiny, it could point the way to making human sperm in the lab for fertility treatments. But some scientists are not convinced by the report, which is published today in Cell Stem Cell.

“The results are super-exciting and important,” says Jacob Hanna, a stem-cell scientist at the Weizmann Institute of Science in Rehovot, Israel. But Takashi Shinohara, a reproductive biologist at Kyoto University in Japan, is among researchers who have doubts about the work: he notes that scientists have struggled to replicate several previous claims that sperm can be made in a dish.

In 2011, molecular biologists led by Mitinori Saitou at Kyoto University reported that they had managed to recreate the first stages of sperm development in a dish. They coaxed mouse embryonic stem cells to become cells that resembled primordial germ cells (PGCs) — an important stage in the development of both eggs and...