ABSTRACT
The thyroid gland is one of the most important endocrine organs that almost all cells of the body are target sites for its hormones, the thyroid state influences markedly both cardiac and skeletal muscles as has been previously reported by many authors. Concerning the skeletal muscles, the hypothyroidism causes atrophy of the muscle fiber and abnormal accumulation of the glycogen. These findings allow a new field for researchers to study the histological picture of the skeletal muscle and the correlation between muscle/body weight ratios in the hypothyroidism. The present study is planned to throw more light on the structure of the skeletal muscle [soleus] and body weight evaluation in the experimentally induced hypothyroid of adult male albino rats. Twenty healthy adult male albino rats, average weight [170 gms each] were used in this study, the body weight evaluated monthly and the skeletal muscle structure was examined histological by light and electron-microscopes after three months of experimentally hypothyroidism. The body weight of the animals were reduced with statistical significant and the skeletal muscle structure affected by experimentally hypothyroidism, where disorganization of the muscle fibers with clear atrophic changes, reduction of the mitochondria and areas of degeneration with abnormal accumulation of glycogen in the skeletal muscle fibers