1. GSF-National Research Center for Environment and Health, Institute of Developmental Genetics, D-85764 Neuherberg, Germany
2. Technology and Development Team for Mammalian Cellular Dynamics, RIKEN Tsukuba Institute, BioResource Center Ibaraki 305-0074, Japan
3. Developmental Biology and Molecular Pathology, University of Bielefeld, 33501 Bielefeld, Germany
4. Center for Animal Resources and Development, Kumamoto University, Kumamoto 862-0976, Japan
5. Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 862-0976, Japan