1. Department of Pharmaceutical Sciences; Kobegakuin University; 1-1-3 Minatojima Chuo-ku Kobe 650-8586 Japan
2. Electron Microscope Laboratory; RIKEN Centre for Developmental Biology; 2-2-3 Minatojima Minami-Cho Kobe 650-0047 Japan
3. Department of Developmental Medicine; Osaka Medical Centre and Research Institute for Maternal and Child Health; 840 Murodo-cho Izumi Osaka 594-1101 Japan
4. Department of Toxicology; Graduate School of Pharmaceutical Sciences; Osaka University; 1-6 Yamada-oka Suita Osaka 565-0871 Japan