Synthetic embryos have been implanted into monkey wombs

Embryos made from stem cells—instead of a sperm and egg—have been created from monkey cells for the first time. When researchers put these “synthetic embryos” into the uteruses of adult monkeys, some showed the initial signs of pregnancy. It’s the furthest scientists have ever been able to take lab-grown embryos in primates—and the work hints that it may one day be possible to generate fetuses this way. 

“This is amazing,” says Susana Chuva de Sousa Lopes, a developmental biologist at Leiden University in the Netherlands, who was not involved in the study. “It’s the first time I’ve seen [synthetic embryos] developed so far, and with such good quality.” It is also the first time such embryo-like structures have been implanted in monkeys.

The team behind the research, Zhen Liu at the Chinese Academy of Sciences in Shanghai and his colleagues, started with embryonic stem cells originally taken from macaque monkey embryos. These cells have been grown in labs for multiple generations and, given the right conditions, have the potential to develop into pretty much any type of body cell, including...