1. Laboratory of Animal Molecular Morphology, Department of Animal Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
2. Department of Anatomy, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku, Tokyo 160-8402, Japan
3. Division of Drug and Structural Research, Life Science Research Center, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
4. Laboratory of Histophysiology, Department of Animal Science, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan