Fig. 5.

Des^−/− muscle contained a higher fraction of ECM compared with wt. A: representative images from wt and des^−/− muscle stained for hematoxylin & eosin (H&E; a and d), laminin (b and e), and collagen type I (c and f). H&E staining revealed a slight but notable increase in inter-fiber spacing in des^−/− sections, which correlated with thicker and brighter staining for laminin and collagen I, suggesting an increase in ECM area. Scale bars = 100 μm. B: area fraction of ECM quantified from laminin-stained sections. There was a small, but significant, increase in the area fraction of the ECM in both young and adult des^−/− muscle. C: although there was an increase in the area fraction of the ECM in both young and adult des^−/− muscle, it was not enough to account for the measured changes in adult bundle stiffness, and calculated ECM tangent modulus was significantly higher in adult des^−/− muscle. *P < 0.05.