Characteristics of the macromolecular components of the extracellular matrix in human hyaline cartilage at different stages of ontogenesis.

The composition of the collagen and proteoglycan components of the extracellular matrix in human rib cartilage under normal conditions at different stages of ontogenesis (from 7 weeks of intrauterine development to 60 years of age) has been analysed. Polyacrylamide gel electrophoresis of collagen CNBr-peptides has shown the presence of type I collagen in embryonal cartilage and a gradual decrease in the quantity of this component relative to type II collagen with increasing age. Analysis of reducible and mature collagen cross-links revealed traces of lysylpyridinoline in addition to hydroxylysylpyridinoline in human rib cartilage. The increase in the content of mature cross-links during ontogenesis was accompanied by a decrease in the content of dihydroxylysinonorleucine. Electrophoretic analysis of proteoglycan monomers revealed four fractions of different mobility and the ratio of these fractions altered in the course of ontogenesis. An increase in the glucosamine/galactosamine ratio in the core proteins was observed with increase in age of the donors. During electrophoretic analysis of the link protein fraction a protein of molecular mass 200 kDa was found. This protein first appeared after 9 weeks of intrauterine development and was present in the rib cartilage at all subsequent stages of embryogenesis. This protein has been identified as tenascin by immunoblotting.