1. Department of Histology and Embryology, Binzhou Medical University, Yantai, Shandong, China
2. Department of Morphology Laboratory, Binzhou Medical University, Yantai, Shandong, China
3. Basic Medicine College, Binzhou Medical University, Yantai, Shandong, China
4. Department of Immunology, Binzhou Medical University, Yantai, Shandong, China
5. Research Institution of Reproductive Medicine, Binzhou Medical University, Yantai, Shandong, China