(a, b) Induced knockout of decorin in DcniKO mice at 1-month age results in similar sGAG reduction and impaired biomechanical properties: (a) reduced sGAG content shown by Safranin-O/Fast Green histology staining and DMMB assay, (b) decreased low-frequency elastic modulus, EL, self-stiffening ratio EH/EL, maximum phase angle, δm, and increased hydraulic permeability, k (mean ± 95% CI from n ≥ 6 animals for each group, *: p < 0.01). (c) Hematoxylin and eosin histology images show no appreciable differences in joint morphology between Dcn−/− and WT cartilage. (d) Uncalcified and total cartilage thickness and cellular density measured from histology images show no significant differences between Dcn−/− and WT. (e) Immunohistochemistry of aggrecan degradation neo-epitopes (TEGE by aggrecanases, VDIPEN by MMPs) on immature, developing cartilage (2-week age) does not detect appreciable signs of aggrecan degradation in both genotypes. Inset is the positive control on the secondary ossification center of WT cartilage at 2-week age. Panels a, b, d: Each data point represents the average value of ≥10 locations measured from one animal.