1. Department of Organ Anatomy, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
2. Institute of Radioisotope Research and Education, Science Research Center, Organization for Research Initiative, Yamaguchi University, Yamaguchi, Japan
3. Department of Health Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
4. Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
5. Department of Anatomy, Akita University Graduate School of Medicine, Akita, Japan