Human embryo models grown from stem cells

A research team headed by Prof. Jacob Hanna at the Weizmann Institute of Science has created complete models of human embryos from stem cells cultured in the lab—and managed to grow them outside the womb up to day 14. As reported today in Nature, these synthetic embryo models had all the structures and compartments characteristic of this stage, including the placenta, yolk sac, chorionic sac and other external tissues that ensure the models' dynamic and adequate growth.