1. Laboratory of Veterinary Anatomy, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1, Kyonan-cho, Musashino-shi, Tokyo 180-8602 Japan
2. Laboratory of Comparative and Behavioral Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, 1-7-1, Kyonan-cho, Musashino-shi, Tokyo 180-8602 Japan