For the first time, a controversial stem-cell research study has been given government permission in Japan. The study aims at implanting modified animal embryos (mice, rats, or pigs) with human ‘induced pluripotent stem’ cells that have the potential to form any part of the body. Human cells will be grown in rat and mouse embryos, then brought to term in a surrogate animal, as part of experiments set to be carried out at the University of Tokyo. This could lay the foundation for the future where human organs for transplant could be grown inside animals. The research team is led by Hiromitsu Nakauchi, a professor of genetics at Stanford University.