The nature of the matrix produced by embryonic chicken chondrocytes in cell culture was studied, and compared with adult and embryonic chicken cartilage. Adult chicken cartilage contains a protein–polysaccharide easily extracted with EDTA–sodium chloride at 4°C. Purification of this macromolecule on Bio-Gel P-300 and Bio-Gel A-50m yielded a progressively more homogeneous species in the ultracentrifuge. It contained mostly chondroitin 4-sulphate, some chondroitin 6-sulphate, and keratan sulphate. Embryonic chicken cartilage was previously shown to contain mostly chondroitin 4-sulphate, some chondroitin 6-sulphate and essentially no keratan sulphate. The matrix produced in chondrocyte cell cultures was shown to contain a protein–polysaccharide with alkali-labile linkages of chondroitin 4-sulphate to the protein core. A fraction was isolated from the matrix with many properties of keratan sulphate.
