ABSTRACT
Twelve adult male albino rats weighing 150-250 gm were used in this study to investigate the histological changes of the kidney of rats on exposure to cadmium and clarify the effect of recovery on renal architecture. The animals were divided into three groups [4 animals each]. The rats of the first group were used as a control group and given saline intraperitoneally, while that of the second group were injected intraperitoneally with cadmium chloride [CdCI[2]] at a dose of 3 mg/kg body wt daily for 14 days and served as treated group. The last 4 animals were left for 3 months after the last injection and those were served as a recovery group. At the time of sacrifice, all the animals were anaesthetized with ether inhalation and their kidneys were carefully dissected and processed for light and electron microscope examination. In cadmium treated animals, light microscope examination of renal cortex revealed that the gomeruli of renal corpuscles were shrunk with widening of their Bowman's spaces. Distortion of the proximal and distal convoluted tubules with vacuolation of their lining epithelium was observed. Loss of brush border of some proximal convoluted tubules and cellular infiltration were seen between some of them. Moreover, many collagen fibers were observed in the interstitium of renal cortex. Ultrastructurally, thickening of the glomerular basement membrane and distortion of feet processes of podocytes. Proximal convoluted tubules had globular mitochondria which lost their basal configuration, some damaged mitochondria and many lysosomes. Also, their nuclei were small with dark heterochromatin. Distal convoluted tubules also had small nuclei with irregular envelop and marginated dense chromatin. Its cytoplasm contained some globular mitochondria. In recovery group, light microscope examination revealed renal corpuscles which formed of tuft of capillaries surrounded by Bowman's capsule. Some cells lining the proximal convoluted tubules have brush border on their apical free surfaces and moderate collagen fibers were noticed in the interstitium. By electron microscope examination, the thickness of the glomerular basement membrane was decreased. Some proximal convoluted tubules had central rounded euchromatic nuclei and its mitochondria took its basal arrangements. Some microvilli were predominant at its luminal border. Also, some distal convoluted tubules showed rounded nuclei with dispersed chromatin and mitochondria were elongated with basal configuration. Cadmium is an important industrial and environmental pollutant that posses a significant health risk to humans and animals. The results of the present work suggested that nephrotoxicity is a major adverse effect of cadmium exposure for long time. So, strict precautions must be taken to prevent cadmium pollution of food and water