An electron microscopical examination of the ageing process of the wing muscles of the House Fly (Musca domestica)

Morphometric analysis was carried out on wing muscles of the House Fly (Musca domestica), ranging from the pupation period to death. In the first week a clear increase was found in the percentage of food reserve consumed by the cell components. Both fibrils and sarcosomes increase in circumference during the first week. The sarcosomes then fuse. After the first week few changes occur. The sarcosomal volume increases in male flies. No disintegration or degeneration of the muscle cells appears with old age. Even the fact that the wing of the male flies exhibits abrasion earlier than that of females cannot be correlated with changes in the wing muscles. The ratio of fibrils to sarcosomes is greater than two to one. This ratio differs in males and females. A gradual decrease in the number of cristae per sarcosome was observed during ageing. This can influence the total activity of the sarcosome. The succinate dehydrogenase reaction is not dependent on age. The presence of two types of sarcosomes is unlikely. Sarcosomes with more cristae are of a darker colour than those with few cristae.