1. Wellcome-MRC Cambridge Stem Cell Institute, Jeffery Cheah Biomedical Centre, University of Cambridge, Cambridge CB2 0AW, UK
2. Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan
3. Division of Mammalian Embryology, Centre for Stem Cell Biology and Regenerative Medicine, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
4. School of Biosciences, University of Nottingham, Sutton Bonington Campus, Nottingham LE12 5RD, UK
5. Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
6. Division of Stem Cell Therapy, Distinguished Professor Unit, Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
7. Laboratory of Medical Bioengineering, Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-mita, Tama, Kawasaki 214-8571, Japan
8. Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1GA, UK
9. Institute for Stem Cell Biology and Regenerative Medicine, Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305USA