Histochemical and Electron Microscopic Studies on Biopsied Muscle from a Patient with Myotonic Dystrophy

Abstract

Microscopic and electron microscopic studies were performed on muscle obtained at biopsy from a 35-year-old man with myotonic dystrophy. Microscopically, in addition to the selective type-1 atrophy which have been emphasized in the literature, changes were observed in type-II fiber, namely the increase in the fiber diameter and the reduction of the fiber population, as well as the destruction of the fiber structure. An electron microscopic examination revealed various diffuse changes in the subcellular structures, such as the fragmentation and the derangement of myofibrils, the swelling and the gathering of mitochodria, and the proliferation of sarcoplasmic reticulum. A lattice-like network of tubules was observed and the correlation of this abnormal structure with myotonic phenomenon was discussed.