Formation of Basement Membranes and Collagenous Fibrils in Peripheral Cystoid Degeneration and Retinoschisis

Author(s):  
W. G�ttinger
Keyword(s):  
Author(s):  
Jared Grantham ◽  
Larry Welling

In the course of urine formation in mammalian kidneys over 90% of the glomerular filtrate moves from the tubular lumen into the peritubular capillaries by both active and passive transport mechanisms. In all of the morphologically distinct segments of the renal tubule, e.g. proximal tubule, loop of Henle and distal nephron, the tubular absorbate passes through a basement membrane which rests against the basilar surface of the epithelial cells. The basement membrane is in a strategic location to affect the geometry of the tubules and to influence the movement of tubular absorbate into the renal interstitium. In the present studies we have determined directly some of the mechanical and permeability characteristics of tubular basement membranes.


Author(s):  
Douglas R. Keene ◽  
Robert W. Glanville ◽  
Eva Engvall

A mouse monoclonal antibody (5C6) prepared against human type VI collagen (1) has been used in this study to immunolocalize type VI collagen in human skin. The enbloc method used involves exposing whole tissue pieces to primary antibody and 5 nm gold conjugated secondary antibody before fixation, and has been described in detail elsewhere (2).Biopsies were taken from individuals ranging in age from neonate to 65 years old. By immuno-electron microscopy, type VI collagen is found to be distributed as a fine branching network closely associated with (but not attached to) banded collagen fibrils containing types I and III collagen (Fig. 1). It appears to enwrap fibers, to weave between individual fibrils within a fiber, and to span the distance separating fibers, creating a “web-like network” which entraps fibers within deep papillary and reticular dermal layers (Fig. 2). Relative to that in the dermal matrix, the concentration of type VI collagen is higher around endothelial basement membranes limiting the outer boundaries of nerves, capillaries, and fat cells (Fig. 3).


Author(s):  
U. Frevert ◽  
S. Sinnis ◽  
C. Cerami ◽  
V. Nussenzweig

Malaria sporozoites, which invade hepatocytes within minutes after transmission by an infected mosquito, are covered with the circumsporozoite (CS) protein, which in all Plasmodium species contains the conserved region II-plus. This region is also found as a cell-adhesive motif in a variety of host proteins like thrombospondin, properdin and the terminal complement components.The CS protein with its region II-plus specifically binds to heparan sulfate proteoglycans (HSPG) on the basolateral surface of hepatocytes in the space of Disse (FIG. 1), to certain basolateral cell membranes and basement membranes of the kidney (FIG. 2) as well as to heparin in the granules of connective tissue mast cells. The distribution of the HSPG receptors for the CS protein was examined by incubation of Lowicryl K4M or LR White sections of liver and kidney tissue with the recombinant CS ligand, whose binding sites were detected with a monoclonal anti-CS antibody and protein A gold.


1960 ◽  
Vol XXXV (III) ◽  
pp. 334-350 ◽  
Author(s):  
U. Waller

ABSTRACT This is a description of ultramicroscopic structures at the base of the thyroid follicle. The structural principle of the subendothelial or interfollicular space, namely basement membranes closely following both the endothelial cells of the capillaries and the epithelial cells of the thyroid, corresponds to that described by other authors in the other endocrine organs. Especially shown are small vesicle like decreases of intensity in the subendothelial space, causing bulges in both the subepithelial basement membrane and the membrane covering the endothelial cell pores thereby forming pseudopores. This membrane is in several parts a double one. The possible role played by the above mentioned structures in the basal secretion of the thyroid epithelial cell is discussed.


2017 ◽  
Vol 68 (7) ◽  
pp. 1481-1484 ◽  
Author(s):  
Radu Mihail Mirica ◽  
Mihai Ionescu ◽  
Alexandra Mirica ◽  
Octav Ginghina ◽  
Razvan Iosifescu ◽  
...  

Obesity involves the growth of adipose tissue cells (adipocytes and preadipocytes), as well as microvascular endothelial cells. Matrix metalloproteinases (MMPs) are relevant ezymes for the modulation of extracellular matrix (ECM) and adipocyte and preadipocytes differentiation. They are elevated in obese patients, generating abnormal ECM metabolism.[1]. This article proposes a thorough study of literature with focus on the important roles of matrix metalloproteinases in the pathophysiology of obesity. The article represents a narrative review based on an English-language PubMed research of the medical literature regardind important aspects of the proposed aim. MMP-2 activity was signi�cantly higher than MMP-9, both activities were detectable. MMP-9 was strongly correlated with body weight parameters before surgery, as well as after significant body weight reduction as a result of bariatric surgery. Concerning MMP-2 and MMP-9 they are also involved in the turnover of basement membranes both those of adipose tissue and endothelial. MMP-9 levels were moderately correlated with HDL cholesterol levels. Taken together, the present data suggest that changes in ECM through MMP-mediated degradation might play a critical role in the adipocyte differentiation process. These findings are detected both in clinical trials and in laboratory animal experiments. It is then tempting to speculate that the adipocyte-derived MMPs might represent a new pharmacological target for the inhibition of adipose tissue growth by inhibiting adipose differentiation as well as angiogenic process.


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