1. Research Center of Developmental Biology and Department of Histology and Embryology, Second Military Medical University, Shanghai 200433
2. Department of Clinical Laboratory, The No. 60 Hospital of PLA, Dali, Yunnan Province 671003
3. Department of Nephrology, Changzheng Hospital, Second Military Medical University
4. Department of Mathematics, Second Military Medical University, Shanghai 200433, P.R. China