1. Laboratory of Anatomy, Faculty of Veterinary Medicine, Department of Basic Veterinary Sciences, Hokkaido University, Sapporo, Japan;
2. Faculty of Animal Science and Veterinary Medicine, Department of Anatomy, Histology and Physiology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh;
3. Department of Histology, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt;
4. Section of Biological Safety Research, Chitose Laboratory, Japan Food Research Laboratories, Chitose, Japan