CIL:39759, Mus musculus, cardiac muscle cell. In Cell Image Library

Transmission electron micrograph of intercalated disks with a desmosome from the atria of mouse cardiac muscle cells. The intercalated disks are where the junction of two opposing membranes of adjacent cardiac muscle cells meet, which are held together by gap junctions and desmosomes. Intercalated disks function to aid in the rapid spread of action potential and in synchronizing muscle contractions. The gap junction allows small molecules and ions such as Calcium, Sodium and Potassium to move from one cell to another creating a direct electrical connection between the two adjacent cells. The desmosome specializes in spot like cell-cell adhesions which work to resist the forces of cardiac muscle expansion and contraction.