Abstract： Objective To investigate the establishment of synapses between the cortical neurons and the neuron-like cells difierentiated from the marrow stromal cells(BMSCs)in a simulated transplantation system in vitro.Methods The BMSCs from green fluorescent protein(GFP)transgenic mice(GFP-GM-BMSCs) were isolated, cultured and purified in vitro.The third passage of GFP-GM-BMSCs were co-cultured with primary cultured cortical neurons and gliai cells in a simulated transplantation system in serum-free medium conmining 2%B27 supplemented with 20 ng/mL basic fibroblast growth factor(bFGF)and 20 ng/mL epidermal growth factor(EGF).On day 10 of the co-culture,FM1-43,a fluorescent dye specific to active synaptic vesicles,was used to observe synapses formation between the cells under fluorescence microscope. Results The GFP.GM-BMSCsco-cultured with the neural cells in the Serum-free medium containing bFGF and EGF differentiated into neuron-like cells 7 days after the co-culture.On day 10 ofthe co-culture,FM1-43 dye-positive synaptic vesicles were foundin the cell culture,locating mostly in the cell body,processes and terminal sffuctures ofthe neuron-like cells. Conclusions The neuron-like cells derived from GFP-GM-BMSCs can form synapses with the coRical neurons in the simulated cell transplantation system in vitro.