1. Laboratory of Veterinary Physiology, Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
2. Department of Theriogenology, Faculty of Veterinary Medicine, Benha University, Kaliobia, Egypt
3. Department of Basic Veterinary Science, The United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan
4. Laboratory of Animal Breeding and Reproduction, University of Tokyo, Tokyo 113-8657, Japan
5. Animal Resource Science Center, Graduate School of Agriculture and Life Science, University of Tokyo, Ibaraki 319-0206, Japan