Comprehensive pathological and quantitative morphometric evaluation of unilateral renal ischaemia reperfusion injury in rat model

Renal ischaemia-reperfusion injury (IRI) is a key precipitating factor in acute kidney injury (AKI) and contributes significantly to the development of chronic kidney disease (CKD). Understanding the temporal dynamics of renal tissue alterations following IRI is critical for determining effective therapeutic strategies. This study aimed to investigate the gross morphological, morphometric and histopathological alterations occurring in rat kidneys at distinct time points following unilateral renal IRI. Twenty-eight adult rats were divided into placebo and IRI groups. IRI was induced by clamping the left renal artery and vein for 60 minutes, while placebo animals underwent sham surgery without vascular occlusion. Animals were euthanised on days 7 and 14 post-surgery. Gross morphology, renal dimensions, organ weight and histopathological changes were evaluated and compared across groups. Placebo animals showed no gross or microscopic renal changes across both time points. In contrast, the IRI group exhibited time-dependent progression of renal injury. At day 7, kidneys showed moderate swelling, congestion and reduced corticomedullary demarcation. Histological findings included tubular degeneration, cast formation and interstitial inflammationindicative of acute injury. By day 14, kidneys displayed severe gross abnormalities including cortical cysts, abscessations and atrophy. Histopathological examination revealed chronic damage with glomerular atrophy, interstitial fibrosis, endothelial injury and abscess formation. The study delineates the temporal evolution of renal damage following unilateral IRI, distinguishing an early phase (day seven) from a later phase (day 14). These findings provide a structural framework for evaluating interventions in experimental nephropathology.