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 (aka desmosomes), 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.
- - "Ultrastructure of the Cell: cardiac muscle, intercalated disk "