1. Department of Cytology and Histology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
2. Faculty of Medicine, Okayama University Medical School, 2-5-1, Shikata-cho, Kita-ku, Okayama city, Okayama 700-8558, Japan
3. Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minami-Josanjima-cho, Tokushima City, Tokushima 770-8513, Japan
4. Division of Biological Science, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502, Japan