Extracellular Matrix (ECM)
Any material produced by cells and secreted into the surrounding medium, but usually applied to the noncellular portion of animal tissues. In broad terms, there are three major components of the ECM: 1) fibrous elements (particularly collagen, elastin or reticulin), 2) link proteins (eg. fibronectin, laminin) and 3) space filling molecules (eg. glycosaminoglycans). The matrix may be mineralized to resist compression (as in bone) or dominated by tension resisting fibers (as in tendon).