Fig. 2

Histopathological changes consistent with dystrophinopathy. a Normal dog at 6 months of age showing uniform fiber size and minimal endomysial connective tissue. b Affected border collie vastus lateralis muscle with dystrophic changes, including myofiber size variation owing partly to larger hyaline fibers (*), increased cellularity likely due to combined effects of inflammation and satellite cell activation (#), and increased connective tissue (+). Hematoxylin and eosin (H&E). Metric bar = 100 μm in both