1. Department of Anatomy; Tokyo Medical University; Shinjuku 6-1-1; Shinjuku-ku; Tokyo; 160-8402; Japan
2. Department of Medical Technology; Kagawa Prefectural University of Health Sciences; Kagawa; 761-0123; Japan
3. Department of Bioenvironmental Medicine, Graduate School of Medicine; Chiba University; Chuo-ku; Chiba; 260-8670; Japan