Articular cartilage is made up of -

Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the whole-body protein content. Tough bundles of collagen called collagen fibres are a major component of the extracellular matrix that supports most tissues and gives cells structure from the outside, but collagen is also found inside certain cells. Collagen has the great tensile strength and is the main component of fascia, cartilage, ligaments, tendons, bone and teeth. 28 types of collagens have been found (so far) in humans. Over 90% of the collagen in the body, however, are of type I, II, III, and IV.