1 Department of Anatomy 1, Sapporo Medical University School of Medicine, West 17, South 1, Chuo-ku, Sapporo, Hokkaido, 060-8556, Japan. ksin@sapmed.ac.jp.
2 Department of Cell Sciences, Research Institute for Frontier Medicine, Sapporo Medical University School of Medicine, West 17, South 1, Chuo-ku, Sapporo, Hokkaido, 060-8556, Japan.
3 Department of Anatomy 1, Sapporo Medical University School of Medicine, West 17, South 1, Chuo-ku, Sapporo, Hokkaido, 060-8556, Japan.