The structure, composition and mechanical properties of cartilage varies with depth from the articular surface and with site on the joint. Within the cartilage the tissue varies with distance from the cell (pericellular, territorial and interterritorial matrix), and the chondrocytes vary with their appearance and in their synthetic activities. It should be noted that there are no sharp distinctions between the three zones through the depth of the cartilage, rather the morphology changes gently across a region that is between adjacent zones.