ABSTRACT
Skeletal muscles were collected from mice 12 weeks after being experimentally infected with Schistosoma mansoni [Sm]. Light microscopic [LM] examination revealed that some of the muscle fibers became disorganized, lost their transverse striation and sometimes contained abnormally centrally located chains of 4-6 nuclei. Moreover, groups of fat cells and inflammatory cells were present in between muscle fibers. Under the electron microscope [EM] the majority of muscle fibers suffered mild to severe ultrastructural changes. Mildly affected fibers showed only abrupt change in the direction of their myofibrils from longitudinal to oblique or even transverse. In severely affected muscle fibers the myofibrils were not only disoriented but also were severely disorganized, The Z lines were thickened and sarcoplasmic reticulum elements were abnormally dilated. Moreover, these severely affected fibers contained degenerated mitochondria and large secondary lysosomes. The ultrastructure of the blood capillaries was severely affected. The walls were thickened because of the increased thickness of both the endothelial cells and their basal laminae. There was also severe reduction of the capillary lumena, which were frequently traversed by intercommunicating endothelial-cell cytoplasmic processes. No granulomata were detected however, few degenerated ova were seen under the EM. The present results confirm at the EM level, for the first time, the reported skeletal muscle - myopathic changes in response to Sm infection