1. Department of Anatomy, Histology and Embryology, Yanbian University Medical College, Yanji, China.
2. Department of Anatomy, Akita University School of Medicine, Akita, Japan.
3. Department of Urology, Kobe University School of Medicine, Kobe, 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.