The Distrbution of Different Molecular Species of Collagen in Fibrous, Elastic and Hyaline Cartilages

The distribution oftype II collagen, considered to be characteristic ofcartilaginous tissues, was determined in various specialized cartilages of the mature pig. The tissues examined were: (1) fibrocartilage of the semilunar meniscus of the knee; (2) elastic cartilage of the external ear; (3) hyaline cartilage of (a) the synoviral joint, (b) the thyroid plate of the larynx, and (c) the nasal septum. The predominant species of collagen in each tissue, whether type I or type II, was appraised semi-quantitatively by analysis of purified collagen solubilized by pepsin and of peptide fragments produced by cyanogen bromide. Cyanogen bromide-derived peptides were characterized by column chromatography on CM-cellulose and by electrophoresis in sodium dodecyl sulphate-polyacrylamide gels. The proportion of each type of collagen was determined precisely by isolating the homologous small peptides, al(I)CB2 and al(II)CB6 [nomenclature of Miller (1973) Clin. Orthop. -92, 260-280], by column chromatography on phosphocellulose and determining their relative proportions by amino acid analysis. Thus collagen of the fibrocartilage ofthe meniscus proved to be all type I; type II was not detected. In contrast, collagen of elastic cartilage of the outer ear, after rigorous exclusion of perichondrium, was type II. Similarly, type II was the only collagen detected in all the mature hyaline cartilages examined.