1. Department of Anatomy, Tokyo Dental College, Tokyo, Japan.
2. Institute of Anatomy and Cell Biology, School of Medicine, Georg-August-Universität Gőttingen, Gőttingen, Germany.
3. Department of Anatomy, Akita University School of Medicine, Akita, Japan.
4. Division of Internal Medicine, Iwamizawa Asuka Hospital, Iwamizawa, Japan.
5. Department of Anatomy and Human Embryology, Institute of Embryology, Faculty of Medicine, Complutense University, Madrid, Spain.