In the present study, the histopathological and Ultrastructural changes occurring in the renal cortical cells of rats following intramuscular injection of ⅛ LD50 (0.0625 mg/kg body weight) of cobra (Naja haje) crude venom were investigated with the light and transmission electron microscopes. Tissues were obtained for investigation at 4 h, 8 h and 12 h time intervals following injection of the venom. Histopathological changes observed after 4 h of venom injection included swelling of the epithelial cells lining the proximal and distal convoluted tubules, widening of their urinary spaces and congestion of glomeruli. Dilatation of the renal tubules, widening of their lumens and disintegration of brush borders of the lining epithelium were demonstrated following 8 h of envenomation. These were associated with cytoplasmic degeneration of epithelia, pyknosis of nuclei and compression of glomeruli. More drastic alterations were seen after 12 h of envenomation. Cytoplasmic regions in epithelial cells lining both types of renal tubules were degenerated together with widening of their lumens, as well as the presence of degenerative parts in the interstitium tissue. Moreover, glomeruli were greatly compressed and pyknosis was prominent in nuclei of mesangial and endothelial cells. The ultrastructural perturbations induced in the proximal and distal convoluted cells following 4h of envenomation were represented by disarray of microvilli, swelling, elongation, as well as coalescence of mitochondria. Severe Ultrastructural changes were observed after 8 h of envenomation. There was a noticeable cytoplasmic degeneration and vacuolation. Most mitochondria were pleomorphic, others were coalesced and large regions of their matrix and cristae were degenerated. Intense cytoplasmic degenerations were seen after 12 h of envenomation. The mitochondria were greatly pleomorphic, degenerated or atrophied. Numerous lysosomes, and lipid droplets were randomly demonstrated. Some of the latter seen in cells of the distal tubules showed the presence of regular spherical vacuoles inside them. The nuclear heterochromatin of the epithelial cells lining proximal and distal tubules was strongly osmiophilic and obviously clumped on the inner leaflet of the nuclear membrane. Large aggregations of deeply stained heterochromatin were also seen scattered in the nucleoplasm. Results from the present investigation showed that cobra envenomation produced time-dependent alterations in the renal cortical tissue and cells. Advanced phases of cellular deterioration surely contribute to dysfunction of the kidney. Such effects which are so drastic may reflect probabilities of renal failure due to cobra envenomation.
Key words: Kidney, Cobra, Venom, Rat, Histopathology, Ultrastructure
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