Glycocalyx

The glycocalyx (pl.: glycocalyces or glycocalyxes), also known as the pericellular matrix and cell coat, is an external organelle consisting of a layer of glycosylated biomolecules called glycoconjugates, such as glycoproteins and glycolipids. These are embedded in and extend outwards from the cell membranes of virtually all cells. Generally, the carbohydrate portion of the glycolipids found on the surface of plasma membranes helps these molecules contribute to cell–cell recognition, communication, and intercellular adhesion.

The glycocalyx is a type of identifier that the body uses to distinguish between its own healthy cells and transplanted tissues, diseased cells, or invading organisms. Included in the glycocalyx are cell-adhesion molecules that enable cells to adhere to each other and guide the movement of cells during embryonic development. The glycocalyx plays a major role in regulation of endothelial vascular tissue, including the modulation of red blood cell volume in capillaries.

The term was initially applied to the polysaccharide matrix coating epithelial cells, known as mucins, but its functions have been discovered to go well beyond that.