1. College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China
2. Department of Obstetrics and Gynecology, Reproductive Medical Center, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510642, China
3. Guangdong Provincial Key Laboratory of Reproductive Medicine, the First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510642, China