Representative images of special staining and RT-PCR results of tri-lineage differentiation in AT-MSCs. AT-MSCs adhering to the bottom of the culture dish were spindle-shaped (A). Following 2 weeks of osteogenic induction, MSCs also showed characteristics of the stroma, including staining with alizarin red, indicating the presence of calcium apatite crystals (B). Observation of the cell pellets that were induced by chondrogenic induction medium for 2 weeks showed a cartilage-like structure that was positively stained with alcian blue (C). Adipogenic induction of the MSCs resulted in adipocyte-like flattened cells with small lipid vesicles that stained positively with oil red O (D).