1. Department of Histology and Embryology, Binzhou Medical University, Yantai, Shandong 264003, P.R. China
2. Quality Department, Shandong Runzhong Pharmaceutical Co., Ltd., Binzhou Medical University, Yantai, Shandong 264003, P.R. China
3. Department of Human Anatomy, Binzhou Medical University, Yantai, Shandong 264003, P.R. China