Fig. 2.

Collagen X-rich matrix. The epiphyseal growth plate is organised in columns of stacked chondrocytes (a). Osteochondromas show less structured organisation (b), and secondary peripheral chondrosarcomas (c) display no clear organisation. Hypertrophic chondrocytes secrete a collagen X-rich matrix, which, ultimately, is replaced by bone (d). In osteochondromas, chondrocytes with a hypertrophic morphology are not always secreting collagen X (e). In secondary peripheral chondrosarcoma, a thick layer of collagen X-rich matrix is observed (f). In osteochondromas and secondary peripheral chondrosarcomas, the thickness of the cartilage cap correlates with the thickness of collagen X-rich matrix (g) (scale bars 10 μm)