1. Department of Pathology, West China Second University Hospital Sichuan University Chengdu China
2. Key Laboratory of Birth Defects and Related Diseases of Women and Children, Sichuan University Ministry of Education Chengdu China
3. Department of Pathology University of Pittsburgh Medical Center Pittsburgh Pennsylvania USA
4. Department of Obstetrics and Gynecology, West China Second University Hospital Sichuan University Chengdu China