Heart muscle cell. Fluorescent deconvolution light micrograph of a section through a dedifferentiating binucleate cardiomyocyte, showing the contractile proteins (green), nuclei (blue) and beta receptor protein development (red). Cardiomyocytes are the muscle cells (myocytes) that make up the cardiac muscle of the heart. Dedifferentiation is the reversion of a specialised cell or tissue to an unspecialized form. Magnification: x800, when printed 10 centimetres wide.