1. Division of Stem Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
2. 21st Century Center of Excellence, Kumamoto University, Kumamoto, Japan
3. Division of Developmental Genetics, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan
4. Department of Reproductive Biology; National Institute for Child Health and Development, Tokyo, Japan
5. Global Center of Excellence, Kumamoto University, Kumamoto, Japan