Background and aims: Malathion induced nephro-toxicity is a challenging process, several mechanisms were contributed. The present study was designed to evaluate the histopathological changes evoked by malathion in renal tissue compared to those induced by malathion plus antioxidants, to clarify the underlying mechanisms, using immunohistochemical staining of proliferating cell nuclear antigen [PCNA] and CD34 Methods: Forty adult male albino rats were divided into four equal groups. Group 1; control. Group 2 received malathion [27 mg/kg/day] orally. Group 3 received malathion plus vitamin E [400 mg] once/day, orally. Group 4 received malathion plus vitamin C [100 mg,] once/day, orally. Animals of all groups were sacrificed after 2 months. Histopathological assessment [H and E and Masson ‘s trichrome] , PCNA and CD34 immunostaining were performed to all groups
Results: Group 2 showed a spectrum of histopathological changes; collapsing glomerulopathy with focal sclerosis, degenerative tubular changes and diffuse vascular congestion. Both groups 3 and 4 showed marked reduction of previous changes. Masson ‘s trichrome stained sections showed more collagen deposition in group 2 compared to groups 3 and 4. Group 2 revealed a decrease in the mean number of total PCNA positive cells [20.8 +/- SD 5.7] [P< 0.001] compared to control group. Groups 3 and 4 showed high significant increase in the mean number of total PCNA positive cells [31.3 +/- SD 5.7 and 31.2 +/- SD7.8] [P<0.001 and 0.004, respectively] . CD 34 immunoslaining of group 2 showed negative to minimal expression compared to moderate to strong intensity of groups 3 and 4