1 College of Animal Science and Technology, Northwest A&F University, Shaanxi Key Laboratory of Molecular Biology for Agriculture, Yangling, Shaanxi, China.
2 Institute of Reproductive Sciences, College of Life Sciences, Qingdao Agricultural University, Qingdao, China.
3 Department of Reproductive Medicine, Qingdao Municipal Hospital, School of Medicine, Qingdao University, Qingdao, China.