Scientists can help fetuses by growing tiny replicas of their organs

WHEN A FETUS shows signs of trouble in the womb, doctors face a precarious task. They must find out what is wrong and how to help without jeopardising the pregnancy. Despite sophisticated modern genetic and imaging tests, many questions are difficult to answer—how severe a malformation is, for example, or how a fetus might respond to treatment. But now scientists have developed a way to create simplified versions of a fetus’s own organs, outside the womb, giving doctors the ability to prod and probe without putting anyone at risk. “For the first time, we can actually access the fetus without touching the fetus,” says Mattia Gerli, a stem-cell biologist at University College London (UCL).