QUANTIFICATION AND IMMUNOLOCALIZATION OF PORCINE ARTICULAR AND GROWTH-PLATE CARTILAGE COLLAGENS

The collagens of growth plate and articular cartilage from 5-6 month o ld commercial pigs were characterised. Growth plate cartilage was foun d to contain less total collagen than articular cartilage as a proport ion of the dry weight. Collagen types I, II, VI, IX and XI are present in both growth plate and articular cartilage whereas type X is found exclusively in growth plate cartilage. Types III and V collagen could not be detected in either cartilage. Type I collagen makes up at least 10% of the collagenous component of both cartilages. There are signif icant differences in the ratios of the quantifiable collagen types bet ween growth plate and articular cartilage. Collagen types I, II, and X I were less readily extracted from growth plate than from articular ca rtilage following pepsin treatment, although growth plate cartilage co ntains less of the mature collagen cross-links, hydroxylysyl-pyridinol ine and lysyl-pyridinoline. Both cartilages contain significant amount s of the divalent reducible collagen cross-links, hydroxylysyl-ketonor leucine and dehydro-hydroxylysinonorleucine. Immunofluorescent localis ation indicated that type I collagen is located predominantly at the s urface of articular cartilage but is distributed throughout the matrix in growth plate. Types II and XI are located in the matrix of both ca rtilages whereas type IX is predominantly pericellular in the calcifyi ng region of articular cartilage and the hypertrophic region of the gr owth plate. Collagen type VI is located primarily as a diffuse area at the articular surface.