Fig. 9

Electron microscopy findings of extensor digitorum longus muscle biopsy in the right leg of Patient 4. Muscle with areas of subsarcolemmal loss of thick filaments with remnants of Z disks (yellow arrow in a), and myofibrillar degeneration (red arrow in e). Autophagic vacuoles with myelinoid figures (yellow arrows in b, c, and e), abnormal mitochondriae with variation in size and shape, dilated and ruptured cristae (yellow arrows in d, h, and i). Mitochondrial paracrystalline inclusions (arrow in g). Nuclear irregularities including pyknosis and nuclear pseudoinclusions, i.e., invaginations of the sarcoplasm inside the irregular nucleus (yellow arrow in f), multiple focal areas of loss of the sarcolemmal membrane (yellow * in h and i) (Transmission electron microscopy a 5,000x, b 6,000x, c 6,000x, d 8,000x, e 8,000x, f 12,000x, g 15,000x, h 40,000x, and i 50,000x)