Lead Compounds Influence on Morphofunctional Features of Kidneys in Ontogenesis

Due to total environmental pollution there is increasing relevance in medical practice of heavy metals and their compounds influence on development of various disorders in humans. The urinary system is very vulnerable to the effects of heavy metal compounds as it is a route of excretion of different chemicals from human and animal bodies. Morphological study of lead compounds effect on embryogenesis of the urinary system in experimental animals seems to be priority area. The article is concerned with the results of scientific studies on lead compounds influence on morphofunctional state of experimental animals' kidneys. It is shown that intake of lead compounds by developing organism even at low doses leads to formation of disordered renal structure, especially glomelural complex, delay in development of renal corpuscles, that is manifested in renal corpuscles size reduction, reducing their number and density of location, lack of differentiation. Number of anses capillaires is reduced. Granular, hyaline droplet, hydropic parenchymal protein degeneration, necrobiosis and necrosis of individual groups of cells are found in urinary tubules epithelium. In some cells nuclei contain small hyperchromic kernels – marks of potential nuclear rhexis. Lumens of urinary tubules are compressed. Influence of lead results in hypertrophy and fibrosis of connective tissue around the corpuscles and surrounding tubules, emergence of lead acetate granules in pararenal structures. Such changes are characterized as focal nephrosclerosis. In some cases cysts formed at the site of necrotic renal corpuscles are found in the renal cortex. In general pathomorphological processes identified in experimental animals are defined as toxic fibroplastic glomerulonephritis. High doses of lead compounds lead to irreversible renal microscopic changes, which are characterized by sclerosis, glomerular atrophy and progressive interstitial fibrosis. Adult rats' use of lead acetate showed development of varying degrees of interstitial nephritis. In macroscopic study kidneys look strangulated and have grainy surface. Histological analysis revealed that areas with distended tubules intersperse with areas of atrophic tubules. Most glomeruli are lost without a trace. Remaining glomeruli are distributed irregularly, some with periglomerular fibrosis. In cells of glomeruli swelling and deformation of organelles in the cytoplasm are observed. Adhesive glomerulitis with varying degrees of damaging is observed in glomeruli: from individual adhesions to complete lumen obliteration of renal glomerulus capsule with formation of intranuclear and cytoplasmic inclusions. Long-term administration of lead compounds in rats results in cytomegaly and karyomegaly development, formation of nuclear inclusions and increase of ferrous-positive granules number in cells of renal proximal tubules. Ultrastructural studies demonstrated mitochondrial swelling and increase of lysosomes number in cells of the renal proximal tubules. Functional disorders in the urinary system of experimental animals under lead compounds administration exhibit reversible aminoaciduria, glucosuria, hyperphosphaturia, uremia, proteinemia. Prolonged or repeated exposure of lead can cause chronic and often irreversible lead nephropathy. Chronic lead intoxication is accompanied by increased urea excretion and significant decrease of urine osmolarity that is result of weakened ability of kidneys to concentrate urine. Thus, lead and its compounds have a quite wide range of adverse effects on morphological and functional state of the urinary system. At the same time, it seems to be important to find ways to reduce the toxicity of lead compounds that enter the body of animals and humans. Under-investigated problem is lead toxicity reduction towards fetus in pregnant women and embryogenesis.