1. Department of Human Anatomy and Histoembryology, College of Basic Medical Sciences Ningxia Medical University Yinchuan China
2. Research Institute of Neural Tissue Engineering, Department of Anatomy Mudanjiang College of Medicine Mudanjiang China
3. Department of Anatomy, College of Basic Medical Sciences China Medical University Shenyang China
4. Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Key Laboratory of Reproduction and Genetics of Ningxia Hui Autonomous Region Ningxia Medical University Yinchuan China