The essentiality of histo- and cytochemical studies of skeletal muscle in the investigation of neuromuscular disease. 1962.

IN THE IXVESTIGATION of neuromuscular disease, histologic examination of skeletal muscle biopsies is generally accepted as an important part both of routine diagnostic procedures and of more specialized research. The purpose of the present report is to establish that the use of histoand cytochemical technics combined with light microscopy is also an essential aspect of both types of investigation. Substantiating evidence is presented in the form of 6 examples, chosen from recent studies, of cytopathologic changes in neuromuscular disease as demonstrated by these technics. Two fundamental types of abnormalities in skeletal muscle are detectable with histoand cytochemical technics: (a) a generalized change of a given reaction, for example, loss of phosphorylase activity, and (b) a localized change of activity confined either to a specific type of muscle fiber (as in the new myopathy with rod-shaped structures) or to certain regions of individual muscle fibers (as in target fibers and central core disease). Further, if the cytochemical technics are s&ciently refined, they may be used to demonstrate the functional activity of fine structural components of the muscle cell. On the basis of such data, predictions can often be made as to the fine structural changes which electron-microscopy will reveal. It must be understood, though, that some cytochemical changes might not be accompanied by changes of fine structure and vice versa. Cytochemisq combined with electron-microscopy would give even more detailed information, but this approach