[A muscle mutant of Drosophila melanogaster: the electron microscopic study of the indirect flight musculature].

Dominant autosomal mutation l(2)M66 DCS induced in Drosophila melanogaster by ethyl-methane-sulfonate was studied. Electron-microscopic studies of asynchronous (fibrillar) and synchronous (tubular) muscles in 24-hour old mutants showed pathological changes in their fine structure. All systems were affected: the fragmentation of the Z-lines, disappearance of protofibrils, degenerative changes of mitochondria, sarcoplasmic reticulum, and the T-system, the appearance of membrane aggregates and lysosomes, the presence of a large amount of glycogen were detected. These changes in the ultrastructure of the flight muscles in mutants are similar to those observed in the process of physiological degeneration of insect muscles.