(MIT Technology Review) – The experiment, at the University of Florida, is an attempt to create a large animal starting only from stem cells—no egg, no sperm, and no conception. A week earlier, “synthetic embryos,” artificial structures created in a lab, had been transferred to the uteruses of all eight cows. Now it was time to see what had grown.

About a decade ago, biologists started to observe that stem cells, left alone in a walled plastic container, will spontaneously self-assemble and try to make an embryo. These structures, sometimes called “embryo models” or embryoids, have gradually become increasingly realistic. In 2022, a lab in Israel grew the mouse version in a jar until cranial folds and a beating heart appeared. (Read More)