1. United Graduate School of Veterinary Sciences, Gifu University, 1–1 Yanagido, Gifu, Gifu 501–1193, Japan
2. Department of Histology, Faculty of Veterinary Medicine, South Valley University, Qena 83523, Egypt
3. Laboratory of Veterinary Anatomy, Faculty of Agriculture, Iwate University, 3–18–8 Ueda, Morioka, Iwate 020–8550, Japan
4. Laboratory of Veterinary Anatomy, School of Veterinary Medicine, Kitasato University, Towada, Aomori 034–8628, Japan