Progressive myofiber replacement by fibrotic and fat tissue in <i>Dmd^mdx</i> rats.

<p>A picrosirius red staining specific for fibrosis was performed on <i>biceps femoris (A–C)</i>, respiratory (<i>D–F</i>) and heart muscle (<i>G–I</i>) samples obtained from wild-type littermate controls (WT) and 3 month-old and 7 month-old <i>Dmd^mdx</i> rats. Compared to control rats (left panel), a progressive increase in the amount of fibrotic tissue (black arrowhead) was noticed in 3 (mid panel) and 7 month-old <i>Dmd^mdx</i> rats (right panel). Note the focal presence of fat tissue infiltration (open arrowhead). In the heart, fibrosis was most marked in papillary muscle of the left ventricle (LV), in the septum and in the ventricular subepicardic area. Picrosirius red staining. Bar = 100 µm (A<i>–</i>F) and 1 mm (G<i>–</i>I).