Histological analysis of H&E-stained skeletal muscle fibers after treatment with bortezomib and muscle collagen morphometry.

A and B: CD showed a greater deposition of connective tissue in the endomysium and perimysium (▸), and the inflammatory cells formed groups or massive lesions (*) with a poor histopathological appearance. C and D: TD showed lower deposition of connective tissue in endomysium and perimysium (▸) and a lower presence of inflammatory cells (*); Original magnification: 10×; bar: 200 µm. E: Mean and SD of muscle collagen morphometry of slides stained with picrosirius red followed by quantitative analysis. Muscle from healthy dogs and TD and CD before (T0) and after (T1) treatment with bortezomib. The p-value was <0.0001 for comparing the collagen at T0 and T1 for CD. At T1 there was a statistically significant difference between the TD and CD, with higher collagen levels in CD (p = 0.0028).