Figure 2

Figure 2 Ultastructural findings in the muscle of patients with Leigh syndrome associated with c. 841delCT SURF1 gene mutation. In a majority of patients (12 of 19 examined cases), several muscle fibres demonstrated distinct subsarcolemmal accumulation of altered mitochondria (B, C). Frequently, the mitochondria were markedly enlarged or elongated (C, D) and exhibited dark matrix with densely packed, concentrically arranged lamellal cristae (D, E). Occasionally, the mitochondrial matrix displaced spaces with amorphous granular material and small, electron-dense, osmophilic granules (D). Extensive accumulation of lipid deposits occurred in association with normal and altered mitochondria (F, G). Some muscle fibres revealed alterations of myofibrils including their focal or widespread disorganisation and/or disruption (A, H, I). Moreover, the tubulofilamentous structures typical of cytoplasmic body formation and subsarcolemmal aggregation of concentric laminated bodies were also found in individual cases (H). Original magnification: A, ×12 000; B, C, F, ×7500; D, G, ×15 000; E, ×10 000; H, ×20 000; I, ×3000.