1. Laboratory of Veterinary Pathology, Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, 1-58 Rinku Orai-Kita, Izumisano, Osaka 598-8531, Japan
2. Institute of Experimental Animal Sciences, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
3. Molecular Genetics Laboratory, Graduate School of Integrated Sciences for Life, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
4. Laboratory of Animal Reproduction and Development, Graduate School of Arts and Science, Iwate University, 4-3-5 Ueda, Morioka, Iwate 020-8551, Japan
5. Veterinary Medical Center, Osaka Prefecture University, 1-58 Rinku Orai-Kita, Izumisano, Osaka 598-8531, Japan