Figure 2.

Schematic illustration of depth-dependent architecture of cartilage tissue. From the superficial zone to the deep zone, the proteoglycan content gradually increases. In the superficial zone, the collagen fibers are aligned parallel to the surface. Collagen fibers in the middle zone are unaligned and tangential to the cartilage surface. In the deep zone, collagen fibers are arranged radially. Finally, the collagen fibers in the calcified zone tend to arborize with little organization and mineralization.⁷²