1. Department of Urology, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
2. MRC Centre for Reproductive Health, Queen’s Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom
3. Current/Present address: Department of Urology, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, P.R. China
4. Department of Urology, The Fifth Affiliated Hospital of Xinjiang Medical University, Wulumuqi, Xinjiang 830011, P.R. China