1. Department of Cell Fate Control Institute of Molecular Embryology and Genetics Kumamoto University 2‐2‐1 Honjo, Chuo‐ku Kumamoto 860‐0811 Japan
2. Laboratory for Embryonic Induction RIKEN Center for Developmental Biology 2‐2‐3 Minatojima‐minamimachi, Chuo‐ku Kobe Hyogo 650‐0047 Japan
3. Animal Resource Development Unit Division of Bio‐function Dynamics Imaging RIKEN Center for Life Science Technologies 2‐2‐3 Minatojima‐minamimachi, Chuo‐ku Kobe Hyogo 650‐0047 Japan
4. Genetic Engineering Team Division of Bio‐function Dynamics Imaging RIKEN Center for Life Science Technologies 2‐2‐3 Minatojima‐minamimachi, Chuo‐ku Kobe Hyogo 650‐0047 Japan
5. Laboratory for Pluripotent Cell Studies RIKEN Center for Developmental Biology 2‐2‐3 Minatojima‐minamimachi, Chuo‐ku Kobe Hyogo 650‐0047 Japan
6. Department of Stem Cell Biology Institute of Molecular Embryology and Genetics Kumamoto University 2‐2‐1 Honjo, Chuo‐ku Kumamoto 860‐0811 Japan
7. Laboratory for Embryogenesis Graduate School of Frontier BioSciences Osaka University 1‐3 Yamadaoka Suita Osaka 565‐0871 Japan