desmosome (macula adherens) A patchlike junction found between adjacent cells in epithelial tissues that helps strengthen the tissue by binding the cells together while allowing movement of materials within the intercellular space. It consists of a discrete cluster of fibres running across a space, some 25 nm wide, between the two cells. On either side, these fibres are anchored beneath the plasma membrane of each cell within a proteinaceous cytoplasmic plaque, from which more fibres extend into the cytoplasm of the cell. Hemidesmosomes are similar to desmosomes but anchor the cell to underlying extracellular matrix. See also cell junction.

desmosome An oval or circular junction between two cells where their respective cell membranes run parallel to one another 30–50 nm apart. Immediately within each membrane there is a plaque of electron-dense material and behind this a less dense area of microfilaments. The space between the membranes contains a glycoprotein. The function of such a junction appears to be that of mechanical attachment.