An intercalated disc is an undulating double membrane separating adjacent cells in cardiac muscle fibers. Intercalated discs support synchronized contraction of cardiac tissue. They can easily be visualized by a longitudinal section of the tissue.

Three types of membrane junctions exist within an intercalated disc—fascia adherens, macula adherens, and gap junctions.

• Fascia adherens are anchoring sites for actin, and connects to the closest sarcomere.

• Macula adherens stop separation during contraction by binding intermediate filaments joining the cells together also called a desmosome.

• Gap junctions allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle.

When observing cardiac tissue through a microscope, intercalated discs are an identifying feature of cardiac muscle.

• Gap junction
• Cardiac muscle

• Template:EMedicineDictionary
• Histology at BU “Ultrastructure of the Cell: cardiac muscle, intercalated disk “

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