Fig. 2

Histological analyses of masseter and tongue muscles of WT and DMD rats. A–F HE- and G, H Masson’s trichrome-stained sections of the masseter muscle of WT and DMD rats. In the masseter muscle of DMD rats, myofiber degeneration and necrosis with infiltration of neutrophils and macrophages at 1 month old, regenerative myofibers with enlarged centralized nuclei and basophilic cytoplasm at 3 months old, and severe fibrosis, confirmed by Masson’s trichrome staining, at 8 months old were observed, respectively. No significant pathological changes were observed in the masseter muscle of WT rats at all ages. I–N HE- and O, P Masson’s trichrome-stained sections of the tongue muscle of WT and DMD rats. In the tongue muscle of DMD rats, regenerative myofibers with enlarged centralized nuclei and basophilic cytoplasm at 1 month old, the regenerative changes accompanied by mild fibrosis at 3 months old, and persistence of mild fibrosis, confirmed by Masson’s trichrome staining, at 8 months old were observed, respectively. No significant pathological changes were observed in the tongue muscle of WT rats at all ages