1. College of Life Sciences, Institute of Reproductive Sciences, Key Laboratory of Animal Reproduction and Germplasm Enhancement in Universities of Shandong, Qingdao Agricultural University, Qingdao 266109, P. R. China
2. College of Horticulture, Qingdao Agricultural University, Qingdao 266109, P. R. China
3. Reproductive Medicine Center, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou 450003, P. R. China
4. Fertility Preservation Lab and Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China