1. Department of Andrology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 510180, P.R. China
2. Department of Andrology, The First Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510080, P.R. China
3. Reproductive Centre, The First Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510080, P.R. China
4. Department of Urology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 51018, P.R. China
5. Department of Urology, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510700, P.R. China
6. Department of Andrology, Ganzhou Municipal Hospital, Ganzhou, Jiangxi 341000, P.R. China