Fig. 2

Central cores and minicores in patients with core myopathies. (A, patient 1, left biceps) Reduced nicotinamide adenine dinucleotide–tetrazolium reductase (NADH-TR) staining of transverse sections of muscle specimens shows the typical central cores. The cores are single, central placed, well-circumscribed, circular regions (arrows) that appeared in almost all fibres. (B, patient 6, right quadriceps femoris) Minicores are demonstrated as multiple foci of ill-defined small areas with deficiency of oxidative activity on NADH-TR staining (arrows). (C, patient 1, left biceps) Electron microscopy shows that the central cores (arrows) contain disorganized myofibrils with Z-line streaming. (D, patient 6, right quadriceps femoris) Electron microscopy shows two minicores (arrows) at the periphery of muscle fibres