Articular cartilage is a hyaline lining on the articular surface of bone ends. It cushions external impacts and reduces
friction between bones to enable smooth and painless joint motion. Chondrocytes are the only resident cell type in cartilage and comprise 1–5% of articular cartilage. These cells produce collagen, proteoglycans, and hyaluronic acid, which are components of the extracellular matrix (ECM) and underlie the mechanical properties of cartilage.

Stem Cell Based Cartilage Regeneration March 2018