الفهرس 
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Abstract
Lead is found at low levels in Earth’s crust, mainly as lead sulfide. Lead is toxic for virtually all organs of the body and has significant debilitating effects on the nervous, renal, hepatic and hematopoietic systems. The liver is considered as one of the target organs affected by lead toxicity owing to its site of storage after exposure. Also, the liver is being one of the major organs involved in the biotransformation and detoxification of toxic substances. Absorbed lead is stored in soft tissues mainly in the liver via the portal vein, so that it is the first organ for which the histological analysis can be used to examine the morphological changes that reflect possible lead effects on somatic cells.
The present study was done to determine the structural damage in the liver by anatomical, histological study and biochemical assay of liver enzyme levels.
Forty five adult male rats were divided into 3 groups. Group I (control group) included 15 rats that were given distilled water by orogastric tube. Group II (experimental group) included 15 rats that were given lead acetate in a dose of 4mg/kg body weight by orogastric tube for two weeks. Group III (experimental group) included 15 rats given lead acetate by the same route and dose for four weeks.
The liver weight was slightly increased in both experimental groups as compared to the control group.
Significant increase of liver enzymes SGPT and SGOT was observed in experimental groups (group II and III). Administration of lead acetate for 2 weeks (group II) induced alteration in the hepatic architecture as evident by some of the hepatocytes appeared with acidophilic slightly vacuolated granular cytoplasm while others showed markedly vacuolated cytoplasm, hypereosinophilic cytoplasm, Mononuclear cellular infiltration was seen in the portal tract. While in Group III, diffuse affection of the hepatic lobule was evident by extensive vacuolation of the hepatocyte cytoplasm, with dark and eccentric nuclei. Others showed kayolytic nucleus, congested central vein, narrow or even obliterated blood sinusoids. The portal area revealed proliferation of bile ducts and congestion of its vessels. The hepatic architecture was disorganized with marked affection of the hepatocytes.
Electron microscopic examination of liver of Group II revealed moderate changes of most liver cells with pleomorphic mitochondria with dense matrix, dilated rough endoplasmic reticulum and dilated smooth endoplasmic reticulum. While sections of liver of Group III rats revealed marked changes involving both the cytoplasm and the nucleus.
It is concluded that lead acetate is toxic to liver and this toxicity is paralleled with increased duration of exposure.