“Microlungs” grown from human tissue might one day help to replace the vast numbers of rats used to check the safety of drugs, cosmetics, and other chemicals.

Cell biologist Kelly BeruBe at the University of Cardiff, UK, has managed to grow human lung cells into flat differentiated layers that resemble the inner lining of the lungs. The ultimate aim is to develop a chip on which thousands of microlungs can be grown then tested simultaneously,