1. Jilin Provincial Key Laboratory of Animal Embryo Engineering, the Centre for Animal Embryo Engineering of Jilin Province, College of Animal Science and Veterinary Medicine, Jilin University, 5333 Xi An Da Lu, Changchun, Jilin 130062, China
2. Department of Histology and Embryology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, China
3. Beihua University, Jilin 132021, China
4. College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China