[A case of central core disease. Electronmicroscopic studies (author's transl)].

A biopsy taken from the right m. gastrocnemius of a sporadic case of central core disease has been investigated by electronmicroscopy. Both longitudinal and cross sections show cores, which are partially in the centre and partially near the sarcolemma of the muscle fibres. These cores are more or less sharply delimited from the intact areas of the muscle fibres. A zone showing a severe destruction of the regularly fibrillar structure is observed in the centre of each core. This destruction zone is surrounded by a transition zone, in which a partial lesion of the fibrillar structure is found whereas the sarcomeric segmentation is preserved. The width of the interfibrillar sarcoplasm is reduced, frequently, however, mitochondria containing cristae of normal structure are observed. The cores are foundlimited by target fibres. Pathogenetically, the damages of z-lines are assumed to be dominant in the formation of the cores.