1. Laboratory of Veterinary Anatomy, Iwate University, 3–18–8 Ueda, Morioka, Iwate 020–8550, Japan
2. Laboratory of Comparative Medicine, Nippon Veterinary and Life Science University, 1–7–1 Kyonancho, Musashino, Tokyo180–8602, Japan
3. Laboratory of Veterinary Anatomy, School of Veterinary Medicine, Kitasato University, 23–35–1 Higashi, Towada, Aomori 034–8628, Japan
4. United Graduate School of Veterinary Sciences, Gifu University, 1–1 Yanagido, Gifu, Gifu 501–1193, Japan