Fig. 5

Genetic iNOS ablation protects against cellular accumulations in the synovium of TNF-Tg female, but not in male mice. Representative H and E-stained slides of female TNF-Tg (a, c) and iNOS^−/−× TNF-Tg (b, d), and their corresponding high magnification images (× 50 and × 100). Note the decrease in synovial thickness (blue arrows); the smaller and fewer in number immune cell clusters (green arrows), and decreased articular cartilage invasion (yellow arrows) in the iNOS^−/−× TNF-Tg knee compared to the TNF-Tg knee. Quantification shows a decreasing trend in total synovial area and cell area within the synovium (e, f). Interestingly, the male TNF-Tg (g, i) and iNOS^−/−× TNF-Tg mice (h, j) do not display any histomorphometric difference in total synovial area and cellular area in the synovium (k, l). Statistical analysis: n = 4–6 per group, Wilcoxon’s rank-sum test, **p < 0.05