1. Department of Histology and Embryology, Basic Medicine College, China Medical University, Shenyang, China
2. Department of Histology and Embryology, Shenyang Medical College, Shenyang, China
3. Department of Biomedicine-Anatomy, Aarhus University, Aarhus, Denmark
4. Department of Biomedical Engineering, College of Fundamental Science, China Medical University, Shenyang, China