Fine Structure of the Human Skeletal Muscle in Myopathy

RECENTLY, progressive muscular dystrophies and other types af myopathies 1-6 have been attracting interest in biochemical, physiologic, and morphologic studies. Although the pathogenesis has not been elucidated, study of the nature of myopathies has been accelerated with current electron microscopic techniques. 7-10 In 1960, Van Breemen 9 reported that early vacuolation of the sarcoplasmic reticulum (SR) was seen as the primary lesion of muscular dystrophy in both light and electron microscopic studies. Platzer and Chase 11 examined muscle of dystrophic mice and found alterations in the muscle fiber, especially disappearance of the sarcolemma, which were observed before clinical manifestations. They concluded that the initial defect might involve the sarcolemma. Fisher et al 12 described mitochondrial changes as the earliest defect. Ultrastructural studies have also revealed new diseases, such as central core disease, 13 myotubular myopathy, 14 and megaconial myopathy. 15,16 Ultrastructural observations in McArdles disease 17 and familial hypokalemic