The ability of articular cartilage to undergo reversible deformation is dependent upon the organization of specific macromolecules within the extracellular matrix. This abundant matrix is elaborated by a small number of chondrocytes which maintain homeostasis via a synchronized balance between anabolism and catabolism. Type II collagen together with smaller amounts of other collagens form the fibrous network of the tissue in which are "entrapped" the aggregating proteoglycans in an underhydrated form. Small amounts of nonaggregating dermatan sulfate containing proteoglycans and matrix proteins are also present in the matrix but their function is less well understood.