1. Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School , Kochi University , Kohasu, Oko-cho, Nankoku, Kochi 783-8505 , Japan
2. Laboratory of Anatomy , Department of Biomedical Sciences , Graduate School of Veterinary Medicine, Hokkaido University , Kita 18, Nishi 9, Kita-Ku, Sapporo, 060-0818 , Japan