Abstract: Objective To observe the mechanism of the bone marrow mesenchymal stem cells (BMSCs) induced by connective tissue differentiate into epithelial cells. Methods Content of epidermal growth factor (EGF) in amnion removed epithelium and foetus intestinal connective tissue were detected by ELISA.BMSCs obtained from fetus aged 16-20 weeks were isolated, cultured and proliferated EM>in vitro/EM>. The DAPI marked P3-BMSCs were planted on the amnion, and added supernatant of intestinal connective tissue or amnion supernatant( both contained final concentration of 30ng/ L EGF)， and exogenous EGF 30μg/L， 30 ng/L， 0， group 1.5 respectively. At the cultivated 7th day, the expressions of cytokeratin(CK)、CK20 in BMSCs were observed with immunofluorescence method and CLSM. Results There were(320.22±0.257)pg，(299.20±0.994)pg EGF in the fetal intestinal connective tissue or amnion/ 100mg respectively. After induced by amnion and supernate of intestinal connective tissue or amnion, the CK and CK20 positive cells in BMSCs were obviously stronger than that in groups induced by amnion and exogenous EGF and in group induced only by amnion, EM>P/EM>0.01 The CK20 positive cells in group induced by amnion and supernate of intestinal connective tissue were much more high than that in group induced by amnion and supernate of amnion,EM> P/EM>0.05 The difference of CK and CK20 positive cells was not statistically significant among the group induced by amnion and exogenous EGF and in group induced only by amnion. Conclusion The direct contact may be one of mechanism tnat amnion induces BMSCs to differentiate int

Key words: Amnion, Connective tissue, Bone marrow mesenchymal stem cell, Induction, Differentiation, Immuno histochemistry, Human fetus