1. Department of Urology , Yinchuan , P.R. China
2. General Hospital of Ningxia Medical University , Yinchuan , P.R. China
3. Ningxia Medical University , Yinchuan , P.R. China
4. Guangzhou First People's Hospital , Guangzhou, Guangdong , P.R. China
5. Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education , Yinchuan , China
6. School of Basic Medical Sciences , Yinchuan , China
7. Ningxia Medical University , Yinchuan , China
8. Department of Obstetrics , Yichun City , P.R. China
9. People's Hospital of Yichun City , Yichun City , P.R. China