1. Division of Morphological ScienceBiomedical Research CenterSaitama Medical University38 Moroyama, Iruma‐gunSaitama350–0495 Japan
2. Department of AnatomySaitama Medical University38 Moroyama, Iruma‐gunSaitama350–0495 Japan
3. Advanced Technology DivisionJEOL Ltd., AkishimaTokyo196–8558 Japan