Fig. 2

Muscle biopsy. A. Electron micrograph of skeletal muscle fibers. In the center an atrophic fiber with activated nucleus is seen. The abnormal myofibrillar structure with aggregates of Z-disc material, i.e. the nemaline rods can be seen as “dark material” (arrows). B. Electron micrograph of a skeletal muscle fiber revealing disorganization of the myofibrils. Nemaline rods consisting of aggregates of Z-disc material are seen (arrows). No cores were identified. No infiltrates of lymphocytes or plasma cells were detected. C. Hematoxylin and eosin staining, revealing the presence of round and angular atrophic fibers (arrow) as well as increased amount of interstitial collagen (D) Gomori trichrome staining revealing a singel ragged red fibre (arrow). (E) Double staining for slow (red) and fast (brown) myosin reveals predominance of type 1 fibres. Atrophy can be observed among both type 1 (red) and type 2 (brown) fibres (arrows). (F) Staining for COX/succinate dehydrogenase shows a few COX negative fibres (arrows)