Figure 2
Qualitative and quantitative analysis of hematoxylin and eosin–stained tibialis anterior muscle sections show pathology as early as 1 week of age. (A) Qualitative histological analyses of tibialis anterior (TA) muscles show pathogenesis beginning as early as 1 day of age in Lama2DyW (DyW) mice. These muscles have large interstitial spaces filled with infiltrating mononucleated cells. Additionally, the muscles tend to lack both consistent fiber sizes and a hierarchical organization of connective tissue. (B) Cross-sectional area measurements show limited growth in DyW mice compared to wild-type (WT) mice during the first 4 weeks of life. WT mice have significantly larger muscle cross-sections at weeks 3 and 4 compared to DyW mice (P < 0.0001 by two-way analysis of variance (ANOVA) (n = 3 to 5)). (C) Counts of the total number of muscle fibers indicate that, as early as postnatal day 1, DyW mice already had a decreased number of muscle cells and that this number increased during development. At all time points, DyW mice had significantly fewer myofibers than their WT counterparts (P < 0.0001 by two-way ANOVA (n = 3 to 5). Note that, though the cross-sectional area does not indicate a diference at week 1, pathology is reflected in the fiber count. Asterisks indicate statistical significance between age-matched DyW and WT animals, hash tags indicate significant changes within the DyW group and Deltas indicate significant changes within the WT group. *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001. These statistical representations also apply other symbols (Δ, #). Bar = 50 μm.