The renal microvasculature (afferent arteriole) and glomeruli were examined and quantitated by two methods in the post-ischemic hydronephrotic (PIH) kidney. The methods used were: 1) an in vivo examination and 2) controlled perfusion-fixation, quantitative vascular casting examined by scanning electron microscopy. The second method was also applied to the vasculature of the contralateral, functional kidney. The goals of the study were to: 1) validate the quantitative vascular casting method by comparing PIH renal microvascular data from the casting method with in vivo values and 2) determine the extent of microvascular dimensional difference of the PIH kidney from its contralateral functional counterpart. It was determined that the casting values were consistent with the data obtained from the in vivo examination of the afferent arteriole and glomeruli. This finding provides further support for the quantitative renal microvascular casting technique. Using that technique it was determined that the dimensions of the microvasculature and glomeruli of the PIH kidney were severely (and significantly, p\u3c0.05) reduced compared to its functional mate. Since these PIH vessels show a significant decrement in size, vascular reactivity and functional data based on the PIH vessels should be looked at cautiously. The vasculature and glomeruli of the PIH kidney might not be totally normal, however structurally, the glomeruli do not appear to be dramatically altered
