1. Department of Reproductive Genetics, Heping Hospital of Changzhi Medical College, Key Laboratory of Reproduction Engineer of Shanxi Health Committee , Changzhi, Shanxi 046000 , P.R. China
2. Department of Gynecology, Heping Hospital, Changzhi Medical College , Changzhi, Shanxi 046000 , P.R. China
3. Department of Comparative Biosciences, University of Illinois at Urbana-Champaign , Urbana, IL 61802 , USA