Background : The widespread usage of microwave in recent life, though useful yet many adverse effects on the functional performance and structural configuration of different organs developed. The muscular system being one of the biggest and superficial system is highly exposed to irradiation by microwaves.
Material and Methods : Thirty adult albino rats were used in this study. They were classified as three groups one control (10 rats) and two experimental (10 rats each). The rats of the first experimental group had exposed to 2.06 GH~/sec. (power density of 170 mW/cm2) irradiation for Vh hour for seven consecutwe days. While rats of the second'experimental group had exposed to the same dose for three weeks. At the end of experiment, animals were anaesthetized and the muscles of the anterior abdominal wail as well as the heart were taken and processed for histological and idtrastructural examination.
Results : Light microscopic examination of skeletal muscle showed wide spaces and splitting of variable sized musucle fibers, intentalization of some nuclei with loss of the others and sarcoplasmic vacuolation after one week of animal exposure. Vacuolation of markedly swelled muscle fibers, internal migration of nuclei, marked disturbance of fiber architecture thai appeared wavy and sarcoplasmic and nuclear degeneration were noted after three weeks. Electron microscopy rei'ealed wide oblique space disturbing the sarcomeric pattern with presentation of the surrounding sarcomers in some specimens. Other specimens clarified sarcoplasmic vacuolation and distortion of Z lines. Some sarcomers were fragemcnled and the mitochondria were swelled with local destruction of their outer membranes. After three weeks, the degeneratii'e changes appeared more intense. Distortion or absence of Z lines, tearing of actin and myocin filaments and condensed mitochondria were evident. In the cardiac muscle, light, microscopy showed mild sarcoplasmic vacuolation with loss of its granular pattern and loss of some nuclei after one week. After three weeks, widening of spaces betmien muscle fibers disconnecting some of their branches zoith destruction of sarcolemmal membrane were present. Ultrastructural examination showed wide spaces between myofibrils, distortion of some Z lines, vacuolation of sarcoplasm and mitochondria after one week. After three weeks many speciemns showed fragmentation and disruption of sarcomeres especially around the intercalated discs and sarcoplasmic degeneration.
Conclusion : Prolonged exposure to microwaves produces muscular degenerative, changes that appeared more vigorous in the skeletal muscle than those of cardiac muscles.
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