ABSTRACT
Desmosomes are punctate, adhesive intercellular junctions that bind cells together and provide membrane anchoring points for the intermediate filament cytoskeleton. They are circular membrane domains of up to 0.5 µm in diameter. The intercellular material or desmoglea occupies a region of about 30 nm wide between the apposed plasma membranes. It has a highly organised ultrastructure consisting of an electron-dense mid line from which cross-bridges extend to the plasma membranes. Close to the cytoplasmic faces of the plasma membranes are dense outer plaques. These are approximately 20 nm in thickness and are the most consistent and easily-recognisable feature of these junctions. At about 50 nm from the plasma membranes are less dense inner plaques that appear to associate with the intermediate filaments. Thus the total thickness of a desmosome from one inner plaque to the other is approximately 130 nm. Desmosomes may be thought of as the “scaffold couplings” that link the intermediate filament cytoskeleton throughout a tissue.
