1. Human Sperm Bank, West China Second University Hospital of Sichuan University, Chengdu, Sichuan 610041, China
2. Department of Andrology, West China Second University Hospital of Sichuan University, Chengdu, Sichuan 610041, China
3. Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, Sichuan 610041, China
4. Department of Urology, West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan 610000, China