Organ culture of adult human articular cartilage. II. The differential rate of glycosaminoglycan synthesis in layers of articular cartilage matrix.

Adult human articular cartilage was maintained in culture for three days and labelled with 35SO4 for the first 48 hours. The explants were sectioned horizontally on the cryostat, and the sections from the top, middle, and deep layers analyzed separately. Autoradiographs were prepared from every twentieth section. The DNA content in each of the three layers was of the same order, but the sulfate uptake and uronic acid content were considerably reduced at the surface. It is suggested that the chondrocytes synthesize matrix appropriate to the layer in which they lie.