The chromophobe renal cell carcinoma is a distinct type of renal cancer presumably derived from the intercalated cell of the collecting duct system and exhibiting a better prognosis than other types of renal cell carcinoma. The filtering structure glomerular filtration barrier has three layers composed of , a , and foot processes. These lobes are represented in the medulla by the renal pyramids. In ultrathin sections they appear limited by a typical unit-membrane structure, and their interior may appear empty or may exhibit material of variable electron opacity. Distribution of anionic sites in glomerular basement membranes: their possible role in filtration and attachment. Neutral proteinase activity produced in vitro by cells of glomerular mesangium.
The distal convoluted tubule and collecting ducts are then largely responsible for reabsorbing water as required to produce urine at a concentration that maintains body fluid homeostasis. The functional significance of the findings is discussed in accordance with the adaptation of the species under study to its harsh desert habitat. Our findings establish a form of nephrogenic diabetes insipidus produced by impaired water permeability in collecting-duct basolateral membrane. Fluid in the filtrate entering the proximal convoluted tubule is reabsorbed into the. From Kanwar 114 Figure 2. The renal calbindin-D28k is dependent upon vitamin D.
Note extensive effacement of epithelial foot process fp architecture. The fixative solutions were systematically varied with respect to sodium chloride concentration, buffer system and glutaraldehyde concentration. In this study, some renal light and electron micro-scopic features were examined in 5 hedgehogs Hemiechinus auritus. We conclude that cells of the distal convoluted tubule do not secrete potassium. Mit Bezug auf moderne Auffassungen vom aktiven Stoffaustausch zwischen Nierenbecken-Inhalt und Nierenmark, wird die Form des Nierenbeckens des Dromedars an Hand von Korrosionsprparaten, Rntgenaufnahmen, Sektionsprparaten und mikroskopischen Schnitten erlutert. The frequency of intercalated cells identified by thin-section criteria was, however, about 35% in controls and unchanged by potassium depletion.
The cells of the collecting duct secrete mucus which may precipitate and bind urate salts in the lumen. Radioimmunoassay revealed that the low dose of aldosterone restored plasma aldosterone to control levels. Podocytes Po send interdigitating foot processes fp that cover capillaries from outside. A new method for isolation of ultrastructurally preserved glomeruli. A: electron micrograph of the slit diaphragm Sd as viewed en face, revealing highly organized zipperlike substructure. Er schließt die granulierten Zellen mit ein, die in der Media der präglomerulären Abschnitte der afferenten und efferenten Arteriolen liegen: die Macula densa und die Zellen des Polkissens.
Each kidney of man is formed of about one million nephrons. In: Extracellular Matrix Biochemistry, edited by K. The spaces between the foot processes match the filtration slits of the capillary endothelial cells. With this technique also shows that podocytes exhibit a protoplasmic extensions which rest on the basal lamina of the endothelium. The structural relationship to the functional capacity of the juxtaglomerular apparatus is discussed. Differentiated microdomains on the luminal surface of the capillary endothelium.
Subsequent revisions of the hypothesis have incorporated recent discoveries of the properties of segments of the renal tubule, particularly the loop of Henle. Sodium is the major positively charged electrolyte in extracellular body fluid. Since the intercalated cells resemble the mitochondria-rich cells, this study was initiated to determine whether or not similar changes occur in the outer medullary collecting duct during chronic metabolic acidosis. Reabsorption in the loop of Henle: The filtrate then enters the loop of Henle descending and ascending limbs , which is responsible for concentrating or diluting the tubular fluid using a process called countercurrent multiplication. Young kidneys also lack thickened, heterogeneous basal laminae associated with the parietal layer of Bowman's capsule, proximal convoluted tubules, and the thin segments of the loops of Henle in adult kidneys.
No structural change of the intercalated cell type in either segment was associated with altered potassium transport. The loop of the mammalian-type nephrons has a descending segment composed of thin and highly interdigitated cells. After collection of physiologic data the kidneys were fixed by in vivo perfusion with glutaraldehyde and processed for electron microscopy. The ultrastructure of intercalated cells I cells varied within a range of different manifestations and the ultrastructural variation of I cells was similar in all the analyzed tubule segments. Diagrams summarizing permeability of glomerular capillary wall to peroxidatic A and dextran B tracers, determined by electron microscopy.
The main characteristic of these cells are the foot process resting on the basal lamina of capillaries. Freeze-fracture and thin-section electron microscopy and morphometry were used to characterize further the response of the rat medullary collecting duct to potassium depletion. Glomerular diseases include , and ; renal tubular diseases include and. Morphology of the juxtaglomerular apparatus and secretory mechanisms. Glucose, amino acids and other substances diffuse out of the epithelial cell down their concentration gradients on passive transporters and are then reabsorbed by the blood capillaries. Size and charge selective permeability defects induced in glomerular basement membrane by a polycation.