This image shows a section of the heart wall. Cardiomyocytes are observed in a longitudinal view. In the inset at the bottom, they are shown in a transverse view. The inset at the upper part shows a magnification of the section in longitudinal view.
Cardiac muscle cells or cardiomyocytes are much shorter than the skeletal striated cells. The limits between cardiomyocytes are dark strips known as intercalar discs. Intercalated discs are composed of different types of cell junctions such as desmosomes, adherent junctions, and tight junctions, which can be found at the edges. Cardiomyocytes contain a nucleus, sometimes two, located in a central position of the cell. In the inset at the upper part, a pattern of dark and clear striations is observed, consequence of the overlapping of the cytoskeleton filaments. Another difference with the striated skeletal cells is that cardiomyocytes are branched cells.