Collagen-proteoglycan relationships in epiphyseal cartilage

Columnar and hypertrophic zones of calf scapular cartilage were studied before and after extraction with 3 M guanidinium chloride (GuCl) and digestion with enzymes which degrade various components of the extracellular matrix. Morphologic and chemical analysis suggests that there are at least two anatomic pools of proteoglycan in this tissue. One, which resides between collagen fibrils, is extractable with GuCl. Another appears attached to collagen by strong bonds and is apparently not extractable with GuCl. This type of collagen-proteoglycan relationship is possibly restricted to epiphyseal cartilage. The morphology of the lacuna is different in the columnar and hypertrophic zones. Proteoglycans in the distal hypertrophic zone are less resistant to GuCl extraction.