cartilage differs form other tissue in that it has no direct blood supply.nutrients are supplied to the cartilage cell the chondroblasts from blood flowing in the adjacent bones and form the synovial fluid in the joint cavity.the glycoprotein materials within the matrix exert strong osmotic force that attracts water together with its dissolved gases inorganic salts and organic materialinto the matrix.in this way materials necessary for normal metabolism are made available to the cartilage cells.the amount of fluid drawn into the cartilage depends on the concentration of glycoproteins in the matrix.the entry of material into cartilage matrix is possible only when no compression force are being applied to the cartilage.when compression is applied water and the various substance dissolved in it are squeezed out.to provide for regular movement of material into and out of the cartilage moderate compression need to be alternatively applied and released in the absence of compression matabolites remain in the matrix and the oxygen content will be lowered.the chondroblasts respond by reducing the secretion of glycoproteins and possible increasing to fibrocartilage.hyaline cartilage covers the articular surface in synovial joint.lubrication between the two surface of hyaline cartilage is facilitated by the secretion of hyaluronic acid by the chondroblasts .a layer or hyaluronic acid molecules for is it viscous convering on the surface of the cartilage with a reserve store of these molecules being retamed in the cartilage atrix when compession is applied to the joint more of these molecules are squeezed onto the surface of the articular cartilage the trapping or synovial fulid in gaps between these molecules ensures that lubrication of the joint is maintained even during weight bearing activity.