Figure 7. Arg-ii-/- mice reveal reduced skeletal muscle fibrosis in aging. (A) Representative masking images showing collagen signals (red) in soleus from old male wild type (wt) and arg-ii-/- (ko) mice. (B, C) Quantification of fibrosis area in both soleus and tibialis from old males and females. A parametric unpaired t-test with Welch’s correction was applied. n = 6–9 mice per group. *p < 0.05, **p < 0.01 between the groups. Scale bar: 250 µm.