Figure 5. Abnormal ultrastructure of the type-II collagen is frequently observed in cartilage and chondrocytes of CSGalNAcT1-null mice.

(A, C and E) Wild-type (Wt) mice; (B, D and F) CSGalNAcT1-null (−/−) mice; at E18.5. Micrographs (A) and (B) were obtained from the resting zone, and (C) and (D) from the proliferative zones. Note that many electron-dense extracellular fibrils (arrows) are seen connecting chondrocytes in the resting (B) and proliferative (D) zones of the epiphysis from null mice, whereas only a few such fibrils are observed in both zones (A; resting zone, and C; proliferative zone) of wild-type mice. At a higher magnification, the wild-type cartilage matrix had collagen fibrils that spread radially (E), whereas cartilage of the null mice had a fine meshwork of twisted cartilaginous fibrils (F). Ch, chondrocytes. Scale bars: (A)–(D), 10 μm; (E)–(F), 1 μm.