الفهرس 
Review of Literature
MORPHOMETRICAL ANALYSISOnly 14 pages are availabe for public view
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Abstract
during the twentieth century environmental exposure to EMFs has increased regularly. However, our knowledge about their biological effects is still containing gaps which should be filled. The parotid gland is the largest salivary gland which showed a higher radiosensitivity when exposed to radiation and xerostomia is one of the most common toxicities after radiation therapy for treating head and neck cancer.
Objective: The goal of this study was to study the histological structure of parotid gland after exposure to low frequency EMFs in adult male albino rats and to clarify the role of vitamin E supplementation with exposure to EMFs.
Materials and methods: Forty adult male albino rats were utilized in this study and were divided into two groups; control group (group I), ten rats were subdivided into two equal subgroups. The animals of subgroup (Ia) were subjected to sham exposure and subgroup (Ib) were injected with vitamin E daily at doses of (50mg/kg bw IM) plus sham exposure. Experimental group (Group II), thirty animals were divided equally into three subgroups. Rats of EMF exposed subgroup (IIa) were exposed to EMF 4 hours/day for successive 30 days, while that of EMF+ vit E supp subgroup (IIb) were supplemented with vitamin E IM daily direct before exposure to EMF and rats of follow up subgroup (IIc) were left for three weeks after cessation of EMF exposure.
Results: Light microscope examination of the parotid sections of EMF exposed subgroup revealed most of the acini with ill defined outlines. Some acinar cells contained darkly stained nuclei and vacuolated cytoplasm. Dilatation of parotid ducts was observed. There were cellular infiltrations and congested blood vessels. Ultrastructural study clarified the light microscopic observations of the same subgroup, some acinar cells appeared with irregular heterochromatic nuclei considered as a sign of apoptosis and their cytoplasm contained electron lucent granules, dilated rER and swollen mitochondria with fragmented cristae. Multiple vacuolations and myelin like figures were observed in some acinar cells. There was limitation of previous changes after vitamin E supplementation and some sort of recovery of acini and ducts in follow up subgroup.