scholarly journals Maturation of the developing renal glomerulus with respect to basement membrane proteoglycans

1987 ◽  
Vol 32 (4) ◽  
pp. 498-506 ◽  
Author(s):  
Brigitte Lelongt ◽  
Hirofumi Makino ◽  
Yashpal S. Kanwar
Keyword(s):  
Basement Membrane ◽  
Renal Glomerulus

scholarly journals FUNCTIONAL EVIDENCE FOR THE EXISTENCE OF A THIRD CELL TYPE IN THE RENAL GLOMERULUS

1962 ◽  
Vol 13 (1) ◽  
pp. 55-87 ◽  
Author(s):  
Marilyn G. Farquhar ◽  
George E. Palade
Keyword(s):  
Basement Membrane ◽  
Kidney Tissue ◽  
Capillary Wall ◽  
Renal Glomerulus ◽  
Sequence Of Events ◽  
Cytoplasmic Bodies ◽  
Cytoplasmic Vesicles ◽  
Spinous Processes ◽  
Luminal Side ◽  
Peripheral Areas

Two types of cells can be recognized on the luminal side of the glomerular basement membrane: the superficial endothelial cells which directly line the lumen and are comparable to endothelia lining the capillaries of other tissues, and the deep cells, ordinarily not in contact with the lumen, which are distinguished by their long cytoplasmic arms extending for some distance in several directions along the capillary wall, numerous spinous processes, and occasional intraluminal pseudopodia. Experiments carried out with electron-opaque tracers indicated that a functional distinction, based on extent of phagocytosis, can be made between the superficial and deep cells, thus supporting the existence of a distinctive "third" cell (in addition to endothelium and epithelium) in the renal glomerulus. Ferritin, colloidal gold, or thorotrast was administered intravenously to normal and, in the case of ferritin, to nephrotic rats. Kidney tissue was fixed at selected intervals from 1 hour to 10 days after the injection and studied by electron microscopy. Within 1 to 4 hours after tracer administration, the particles which did not traverse the glomerular capillary wall gradually accumulated in the less compact, inner strata of the basement membrane and the large spongy areas of axial regions. After 1 day the concentration of circulating tracer declined and the peripheral areas of the capillaries became relatively free of particles while large accumulations developed in the axial regions. During this period increasing quantities of ferritin were taken up by the deep cells and were found within large and small sized invaginations of their cell membrane or concentrated within cytoplasmic vesicles, vacuoles, multivesicular and dense bodies. At the same time the deep cells showed increased numbers of intraluminal pseudopodia. Within 2 to 4 days the deposits in the spongy areas were cleared and concomitantly increased quantities of tracer appeared in the deep cells within dense cytoplasmic bodies, some of which were more compact than before. When ferritin was given to nephrotic animals the sequence of events was generally the same except that the ferritin deposits at any given period were more massive, their incorporation into the deep cells occurred primarily by means of large pockets 1 to 2 µ in diameter and their clearance from the spongy areas was slower. In normal as well as in nephrotic animals, the phagocytic activity of the superficial endothelium was negligible when compared to that of the deep cells.

scholarly journals TRANSPORT OF GLOBIN BY THE RENAL GLOMERULUS

1964 ◽  
Vol 120 (6) ◽  
pp. 1129-1138 ◽  
Author(s):  
Max G. Menefee ◽  
C. Barber Mueller ◽  
Allen L. Bell ◽  
Joseph K. Myers
Keyword(s):  
Endothelial Cells ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Basement Membranes ◽  
Renal Glomerulus ◽  
Thin Sections ◽  
Characteristic Appearance ◽  
Pass Through ◽  
Surrounding Membrane ◽  
Glomerular Capillaries

Purified human globin injected into rats forms aggregates which are identifiable by their characteristic appearance in thin sections in the electron microscope and by their positive autoradiographs when the globin is tritiated before injection. Globin is taken up by endothelial cells of glomerular capillaries and is transported across the cell within the limits of a surrounding membrane. Globin is rarely seen to pass through fenestrations. Globin is also taken into the stalk region where it is seen usually within the sponge fibers and only occasionally within stalk cells. Globin is seen in all stages of passage through the basement membranes and sponge fibers, which are not deformed by its passage. On the basis of the findings presented here and by others, it is postulated that the basement membrane and sponge fibers consist of a thixotrophic gel. After traversing the basement membrane, the globin passes between foot processes of the epithelial cells. The slit membranes are deformed by this passage and thus appear to be distinctive structures. The globin is next found free in Bowman's space; the earliest aggregates are seen there within 1 minute after injection. Globin taken up in the stalk region is slowly discharged and very little is found there 6 hours postinjection.

The Mesangium of the Renal Glomerulus

1971 ◽  
Vol 16 (10) ◽  
pp. 428-437 ◽  
Author(s):  
S. L. Galbraith
Keyword(s):  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Renal Glomerulus ◽  
Frog Kidney

The transport of injected thorotrast across the glomerulus of the frog kidney was studied following destruction of its mesangium. The results suggest that the mesangium contributes to the physiological integrity of the glomerular basement membrane and may therefore be a factor in the aetiology of glomerulonephritis.

scholarly journals THE FINE STRUCTURE OF THE RENAL GLOMERULUS OF THE MOUSE

1955 ◽  
Vol 1 (6) ◽  
pp. 551-566 ◽  
Author(s):  
Eichi Yamada
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Basement Membrane ◽  
Osmium Tetroxide ◽  
Thin Sheet ◽  
Renal Glomerulus ◽  
Golgi Bodies ◽  
Glomerular Capillary ◽  
Cellular Components ◽  
Filtration Surface

Sections of mouse renal glomerulus fixed by perfusion with buffered osmium tetroxide solution have been studied with the electron microscope. Four components are recognized in the mouse glomerulus: epithelium, basement membrane, endothelium, and intercapillary cell. The three cellular components all display in their cytoplasm mitochondria, Golgi bodies, endoplasmic reticulum, and uncharacterized vesicles. The concepts of Hall, of Pease, and of Rhodin regarding the glomerular filtration surface are confirmed. The epithelial cells are characterized by intricate, branching, interdigitating ridge-like processes or pedicels, the summits of which press against the urinary surface of the basement membrane, covering the glomerular capillary tuft almost completely except for narrow spaces about 200 to 300 A wide between the processes. These spaces are termed the epithelial filtration slits, and are bridged by a very delicate gossamer-like membrane about 30 A thick,—the filtration slit membrane. The basement membrane is interposed everywhere between epithelial processes and endothelium, and between epithelial and intercapillary cells. The basement membrane of the filtration surface of the glomerular capillary has smooth surfaces and is about 800 A thick. It consists of three layers—a thick central lamina densa, appearing to have a very delicate felt-like structure, flanked on each side by thinner lamina rara externa and lamina rara interna. This membrane continues to the intercapillary space and makes a complicated sponge-work of varying thickness in which the intercapillary cells are enmeshed. The endothelial cells are of moderate thickness in the nuclear region, but send out thin sheet-like extensions over the filtration surface. These extensions are about 300 to 400 A thick and are characterized by numerous round endothelial filtration pores about 500 to 1000 A in diameter. The intercapillary tissue or mesangium is composed of the network of the basement membrane and the intercapillary cells. The intercapillary cells, with characteristic fine fibrillar cytoplasm, make contact with epithelial and endothelial cells and are enmeshed within the network of the basement membrane. Rounded processes of intercapillary cells penetrate into the endothelial cell through the basement membrane, and may even perforate entirely through the endothelium. Such processes are called (after Zimmermann) the intracapillary colliculi. In the endothelial cytoplasm close to the intracapillary colliculi are many dense endothelial juxtacollicular vesicles and caveolae. The cell boundaries of the endothelial cell resemble terminal bars. Some physiological speculations relating to glomerular structure are advanced. The description of Zimmermann (54), based on a light microscope study, is confirmed in many respects.

scholarly journals GLOMERULAR PERMEABILITY

1969 ◽  
Vol 130 (2) ◽  
pp. 381-399 ◽  
Author(s):  
M. A. Venkatachalam ◽  
Morris J. Karnovsky ◽  
Ramzi S. Cotran
Keyword(s):  
Epithelial Cells ◽  
Basement Membrane ◽  
Intercellular Junctions ◽  
Ultrastructural Localization ◽  
Basement Membranes ◽  
The Other ◽  
Serial Sections ◽  
Renal Glomerulus ◽  
Glomerular Permeability ◽  
Urinary Space

Wistar/Furth rats were made nephrotic by daily administration of amino-nucleoside of puromycin, and the ultrastructural localization of horseradish peroxidase (mol wt 40,000) in the renal glomerulus was studied from 1 min to 20 hr after intravenous injection of the tracer. In control rats, peroxidase permeated the endothelial fenestrae, the basement membrane, and the epithelial slits, and was present in tubular lumina. Nephrotic glomeruli showed relatively normal basement membranes, extensive fusion of foot processes with formation of "close" intercellular junctions, and large vacuoles and pockets in epithelial cells. On serial sections some of the epithelial vacuoles communicated on one side with the extracellular space overlying basement membrane, and on the other side with the urinary space. In nephrotic animals, peroxidase permeated the basement membrane and the close junctions, and was present in many of the vacuoles and pockets as early as 1 min after injection. Only small numbers of peroxidase-positive vacuoles remained in. epithelial cells 1 hr or more after injection of the tracer. It is suggested that the epithelial pockets and vacuoles form pathways across which leaking proteins can be transferred across the epithelium into the urinary space. Epithelial vacuoles may also be absorption droplets designed to "conserve" leaking proteins, but this function was not prominent in our experiments with peroxidase.

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