The hexasamine content and swelling ratio of adult bovine articular
cartilage were determined as functions of depth. Progressing from the
surface downward, the hexosamine content increased rapidly to a depth
equivalent to approximately 30 to 35 per cent of the total thickness of the
uncalcified portion of the tissue, and thereafter decreased at a less rapid
rate. The swelling ratio was relatively constant throughtout the first
quarter of the tissue but diminished thereafter. At depths below 35 per
cent, the curve for the decrease in swelling ratio with depth was similar
in form to that for the decrease in hexosamine content. Considering the
factors that determine the swelling ratio of polyelectrolyte gels, it is
proposed that progressing down from the surface, the interaction between
the macromolecular components of the tissue is increased to a depth
equivalent to about one-third of the total thickness of the cartilage.