[Juxtaglomerular blood flow pathway in the kidney (comparative-anatomical and age-related aspects)].

To observe the formation of blood flow in the juxtaglomerular pathway in comparative-anatomical and age-related aspects, 484 kidneys from the representatives of the five classes of vertebrates, 50 kidneys of human fetuses and 193 kidneys of normal individuals of different ages were studied. Macro-microscopic, histological and morphometric methods were used. In all the mammalian animal species, the significant development of vascular glomeruli and peritubular capillaries was observed. In human kidneys, the relative content of cortical and medullary arterial vessels was maximal in juvenile age. With age, this parameter was found to decrease both in renal cortex and medulla. The differentiation of renal tissue into the cortex and the medulla, that began in birds and was finally formed in mammals, explains the appearance of cortical and juxtamedullary blood flow pathways. During the antenatal period of human development, renal juxtaglomerular pathway of blood flow prevails over the cortical one. The diminished significance of juxtamedullary pathway of blood flow in elderly and senile age determines the decreased adaptive capacities of intraorgan renal arterial bed in the norm.