Fig. 1.

Spontaneous cartilage degeneration in Sulf^−/− mice. (A) Knee joints were harvested from WT and Sulf^−/− mice at 1.5, 3, and 6 months of age to determine spontaneous development of changes in joint tissues. Sections were stained with safranin O and cartilage degeneration was quantified by using a modified Mankin score and a summed score (n = 6–8 animals per time point). (B) At 6 months, Sulf^−/− mouse knee joints showed significantly more severe cartilage degeneration than WT. ^†, P < 0.01. (Scale bars: low magnification, 200 μm; high magnification, 50 μm.)