Histology of the kidneys

Kidney coated capsule with two layers and consisting of collagen fibers with a small admixture of elastic, and a layer of smooth muscle in depth. The last pass directly into the muscle cells star veins. The capsule is pierced blood and lymphatic vessels, closely associated with vascular system not only kidneys, but also perinephral fiber. Structural unit of the kidney is the nephron, which includes the ball together with the capsule Shumlyanskiy-Bowman (which together constitute the renal body), convoluted tubules of the first order, the loop Henle, convoluted tubules II order, direct tubules and collecting tubules that in a Cup of kidney (printing. table, Fig. 1 - 5). The total number of nephrons - up to 1 million

cut the kidneys
Fig. 1. Frontal section of the kidney (scheme): 1 - capsule; 2-cortical substance; 3 - the medulla (pyramid Malpighi); 4 - renal pelvis.
Fig. 2. Cut through the share of the kidneys (low magnification): 1 - capsule; 2 - cortical substance; 3 - cross cut convoluted tubules of the urinary; 4 - cut longitudinally direct urinary canals; 5 - the glomeruli.

Fig. 3. Cut through the plot the core substance (large increase): 1 - the glomerulus; 2 - the outer wall of the capsule up; 3 - the main Department urinary canaliculi; 4 - insertion Department urinary canaliculi; 5 - brush border.
Fig. 4. Cut through the outer part of the brain substance (large increase): 1 - thick division Genle hinges (ascending knee); 2 - a thin Department Genle hinges (downside knee).
Fig. 5. Cut through the deep part of the brain substance (large increase). The collective of the tube.

Clew formed blood capillaries, which breaks up bringing of the arterioles. Gathering in a single efferent tracts, capillaries give up the efferent arterioles (vas efferens), caliber which much is already bearing (vas afferens). With the exception of the glomeruli, situated on the border between cortical and brain layers, in the so-called juxtamedullary area. Juxtamedullary the glomeruli have larger dimensions, and the caliber of afferent and efferent vessels is the same. Due to their location juxtamedullary the glomeruli are particularly circulation that is different from that of cortical clubockov (see above). Basal membrane of the glomerular capillaries dense, homogeneous, with the thickness up to 400 + contains PAS-positive mucopolysaccharides. Endothelium cells often vacuolation. Electron microscopy of the endothelium found round holes up to 1000 + in diameter, in which blood is in direct contact with the basal membrane. Loop capillaries suspended inside a peculiar bruecke - mezangiuma, representing a complex of hyaline records of proteins and mucopolysaccharides, between which there are cells with small engines and scant cytoplasm. Clew capillaries covered with flat cells with sizes up to 20-30 MK with light cytoplasm closely in contact with each other, which form the inner layer capsules Shumlyanskiy-Bowman. This layer is connected with capillary system of canals and lacunae, which circulates makeshift urine filtered out of the capillaries. The outer layer capsules Shumlyanskiy-Bowman presents flat epithelial cells that the place go to the main Department become higher, cubic. In the field of vascular pole up are a special kind of cells that form the so-called endocrine systems kidney - juxtaglomerular apparatus. Some of these cells - grained epitelialna - located in 2-3 rows, forming the clutch around bringing arterioles before her entrance into a ball., Number of granules in the cytoplasm of them varies depending on the functional state. Cells of the second kind is a small flat, elongated, with a dark core is placed in the corner formed by generating and efferent arterioles. These two groups of cells, according to modern views, arise from smooth muscle cells. The third type-a small group of tall, elongated cells with nuclei, located at different levels, as if piled on each other. Are these cells to the site of the crossing Genle hinges in the distal convoluted tubule and dark patches, educated piled cores are designated as macula lutea densa. Functional significance yukstaglomerulyarnogo apparatus may lead to development of renin.
Wall convoluted tubule I order presents cubic epithelium, the basis of which the cytoplasm has radialno striated. Parallel rectilinear strongly developed folds basal membrane form a kind of camera that contain mitochondria. Brush border in the epithelial cells of proximal nefrona formed parallel protoplasmatic threads. Functional meaning it is not studied.
Loop genre has two tribes-the downward thin and thick ascending. They are lined with flat epithelial cells, bright, well perceiving aniline dyes with very little grain of cytoplasm, which sends into the lumen of the tubule small and short microbikini. The border of the descending and ascending knee Genle hinges corresponds to the location of the macula lutea densa ukstaglomerulyarnogo system and shares the nephron in proximal and distal.
The distal nephron includes convoluted tubules II order, is virtually indistinguishable from a convoluted tubule I order, but devoid of the brush edges. Through a narrow Department direct tubules they are collectively tubes lined cubic epithelium with light cytoplasm and large light nuclei. Collective tubes open 12 - 15 moves into the cavity of small cups. In these areas, their epithelium is high cylindrical goes double row epithelium of cups, and the last in the transition bladder epithelium of the renal pelvis. At the proximal Department of nephron falls main reabsorption of glucose and other substances that have a high threshold intake, at the distal-suction main quantity of water and salts.
Muscular layer of the Cup and of the renal pelvis is closely connected with the muscles of the inner layer of the renal capsule. The vaults of the kidneys (fornices) lack of muscle fibers, represented mainly by the mucous and submucous layer and are therefore the most vulnerable point of the upper urinary tract. Even with a slight rise vnutriorgannogo pressure can be observed breaks vaults buds with break-content pelvis into the substance of the kidneys, the so - called pierremarie refluxes (see).
Interstitial connective tissue in the cortical layer extremely poor, composed of fine reticular fibers. In cerebral layer it is more developed and includes the collagen fibers. Cellular elements in stroma little. Stroma heavily penetrated by blood and lymph vessels. In the renal arteries has microscopically clearly divided into three shells. Dating formed by endothelial ultrastructure of which is almost similar to that in the glomeruli, and the so-called subendothelial cells with fibrillar cytoplasm. Elastic fibers form a powerful inner elastic membrane - two - or three. Outer sheath (wide) presents collagen fibers mixed with certain muscle that no sharp borders are moving in the surrounding connective tissue and muscle bundles kidneys. In adventitia blood vessels go lymphatic vessels, of which also contain large coorespondence muscle bundles in their wall. In the veins of the three shells conditional, adventitia almost never expressed.
The direct relationship between arteries and veins are presented in the kidneys two types of arterio-venous anastomoses: direct connection of arteries and veins in juxtamedullary the circulation and arteriovenous anastomoses type of guard arteries. All of renal vessels - blood and lymph - accompanied nerve plexus, which form during their thin, ramified network of ending in the basal membrane tubules of the kidney. Especially dense neural network obletaet cells yukstaglomerulyarnogo apparatus.