Typical histopathological presentation of skeletal muscles of GRMD dogs, 3, 5 and 12 month-old and corresponding images at an MRI scale. Progressive tissue changes characteristic of the disease evolution elicited some heterogeneity in the tissue aspect. This heterogeneity increases with age as the disease progress and the muscle tissue is replaced by fibrosis and some adipose tissue infiltration. (A-C) Hemalun eosin saffron and (D-F) Mean grey level of the histological images A, B and C were transformed to images D, E and F at an MRI resolution. Mean value was sampled using region of interest of 320 pixels (A-B) or 648 pixels (C) and consecutively converted to greyscale. Bars = 100 μm (A-B) and 200 μm (C). Pixel size = 0.91 μm (A-B) and 0.78 μm (C) for histological images, 290 μm (D-E) and 500 μm (F) for MRI-simulated corresponding images.