Scientists have grown structures made of stem cells that mimic a 21-day-old embryo. (Naomi Moris)

Lab-grown cells mimic crucial moment Gastruloids, embryo-like structures created from stem cells, are the first to form a 3D assembly that lays out how the body will take shape. The gastruloids developed rudimentary components of a heart and nervous system, but lack the components to form a brain, as well as cell types that would make them capable of becoming a viable fetus. The artificial structures avoid ethical concerns about doing research on human embryos. They could shed light on the causes of pregnancy loss and early developmental disorders, such as congenital heart conditions and spina bifida. Nature | 4 min read Reference: Nature paper