STRUCTURAL AND STEREOLOGICAL ANALYSIS OF RAT-THYROID GLAND AFTER EXPOSURE TO AN ELECTROMAGNETIC-FIELD

Considering that the thyroid gland is one of the most sensitive organs to ionizing radiation, we decided to investigate the effects of a low frequency electromagnetic field (LF-EMF) as non-ionizing radiation on the thyroid structure of male rats exposed for five months to a 50 Hz magnetic field of decreasing intensity 500 mu T to 50 mu T along thei r cages. Stereological analysis showed a significant reduction in: vol ume density of the follicles (p <0.05), volume density (p <0.01) and t hickness (p <0.01) of the follicular epithelium, as well as the thyroi d activation index (p <0.005) while the volume density of the colloid (p <0.01) and interfollicular tissue (p <0.05) were significantly incr eased compared to the control. The most prominent cytological changes in the thyroidal follicular cells were the absence of apical protrusio ns, the rare presence of intracellular colloid droplets and the extrem ely low follicular epithelium in some areas of the glands. These morph ometrical and morphological alterations indicate that long-term exposu re to LF-EMF induced disturbance of normal thyroidal structure.