1. Department of Basic Pathology, Fukushima Medical University, Fukushima 960-1295, Japan
2. Division of Brain Structure and Function, Research Center for Child Mental Development, School of Medical Science, University of Fukui, Fukui 910-1193, Japan
3. Division of Cell Structure, National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan
4. Department of Physiological Sciences, School of Life Science, SOKENDAI (Graduate University for Advanced Studies), Okazaki, Aichi 444-8585, Japan