Fig. 7. Newt cardiomyocytes transdifferentiate into skeletal muscle cells in regenerating newt limbs. Immunofluorescence staining of DiI-labeled cardiomyocytes (red) with anti the skeletal-muscle-specific anti-sTnI antibody (A,B,I,J; green) and with the cardiac-muscle-specific anti-cTnT antibody (C,D,K,L; green). Hoechst 33342 counterstaining was used to localize all nuclei on the cryosections. Inlets in C and D, are positive controls for cTNT staining using sections derived from the heart. Note the rapid downregulation of cTnT in transplanted cardiomyocytes and the upregulation of skeletal-muscle-specific proteins in DiI-labeled cells 15 days after transplantation. The formation of cardiomyocyte-derived skeletal myotubes are clearly visible 30 days after transplantation. Bars, 100 µm.