Intercalated discs or lines of Eberth are microscopic identifying features of cardiac muscle. Cardiac muscle consists of individual heart muscle cells (cardiomyocytes) connected by intercalated discs to work as a single functional syncytium. By contrast, skeletal muscle consists of multinucleated muscle fibers and exhibits no intercalated discs. Intercalated discs support synchronized contraction of cardiac tissue in a wave-like pattern so that the heart can work like a pump. They occur at the Z line of the sarcomere and can be visualized easily when observing a longitudinal section of the tissue.

Structure

Intercalated discs are complex structures that connect adjacent cardiac muscle cells. The three types of cell junction recognised as making up an intercalated disc are desmosomes, fascia adherens junctions, and gap junctions. All of these junctions work together as a single unit called the area composita.

Clinical significance

Mutations in the intercalated disc gene are responsible for various cardiomyopathies that can lead to heart failure. Ruptured intercalated discs, when seen on histopathology, have two main causes: Additional signs indicating forceful myocardial contraction are: