Fig.4. Cell lineage studies.
A. Evidence that induced cardiomyocytes are derived from satellite cells. Pax7 expressing cells were labeled by treating the Pax7-CreER;mT/mG mice with tamoxifen. The green label indicates that cTnT-positive cardiomyocytes formerly expressed Pax7. Scale bar 25μm. B. Evidence that induced cardiomyocytes are derived from the secondary heart field. Satellite cells were prepared from Isl1-Cre;mTmG mice and then sorted for GFP expression, and subjected to the cardiomyocyte differentiation procedure. The NKX2.5 and cTnT-positive cells must be derived from cells that had expressed Isl1 in vivo. Scale bar: 25μm.