Fig. 4.

Young and adult des^−/− muscle had increased collagen content compared with wt. There was an increase in collagen content in the des^−/− muscle with age that mirrored the increase in stiffness seen in the bundle data (compare with Fig. 2B). Collagen content nearly doubles in the adult des^−/− compared with the adult wt as does bundle tangent modulus. There is a significant genotype-age interaction determined by two-way ANOVA. *P < 0.05.