1. Center for Reproductive MedicineShandong University Jinan Shandong 250012 China
2. National Research Center for Assisted Reproductive Technology and Reproductive GeneticsShandong University Jinan Shandong 250012 China
3. Key Laboratory of Reproductive Endocrinology of Ministry of EducationShandong University Jinan Shandong 250012 China
4. Department of Molecular and Cellular BiologyHarvard University Cambridge MA 02138 USA
5. Advanced Medical Research InstituteShandong University Jinan Shandong 250012 China
6. State Key Laboratory of Microbial TechnologyShandong University Qingdao Shandong 266237 China