scholarly journals Structural features of alveolar wall basement membrane in the adult rat lung.

1981 ◽  
Vol 91 (2) ◽  
pp. 427-437 ◽  
Author(s):  
C A Vaccaro ◽  
J S Brody
Keyword(s):  
Basement Membrane ◽  
Ruthenium Red ◽  
Basement Membranes ◽  
Alveolar Wall ◽  
Type I ◽  
Type Ii ◽  
Rat Lung ◽  
Anionic Sites ◽  
Lamina Densa ◽  
Adult Rat

The ultrastructural characteristics of alveolar (ABM) and capillary (CBM) basement membranes in the adult rat lung have been defined using tannic acid fixation, ruthenium red staining, or incubation in guanidine HCl. ABM is dense and amorphous, has 3- to 5-nm filaments in the lamina rara externa (facing the alveolus) that run between the lamina densa and the basal cell surface of the epithelium, has an orderly array of ruthenium red-positive anionic sites that appear predominantly (79%) on the lamina rara externa, and has discontinuities beneath alveolar type II cells but not type I cells that allow penetration of type II cytoplasmic processes into the interstitium of the alveolar wall. The CBM is fibrillar and less compact than ABM, has no lamina rara filaments, and has one fifth the number of ruthenium red-positive anionic sites of ABM that appear predominantly (64%) overlying the lamina densa. Incubation of lung tissue with Flavobacterium heparinum enzyme or with chondroitinase has shown that ABM anionic sites represent heparan sulfate proteoglycans, whereas CBM anionic sites contain this and other sulfated proteoglycans. The CBM fuses in a local fashion with ABM, compartmentalizing the alveolar wall into a thick and thin side and establishing a thin, single, basement-membrane gas-exchange surface between alveolar air, and capillary blood. The potential implications of ABM and CBM ultrastructure for permeability, cell differentiation, and repair and morphogenesis of the lung are discussed.

Immunocytochemical localization and identification of the major surfactant protein in adult rat lung.

1981 ◽  
Vol 29 (2) ◽  
pp. 291-305 ◽  
Author(s):  
M C Williams ◽  
B J Benson
Keyword(s):  
Alveolar Macrophages ◽  
Gradient Centrifugation ◽  
Surfactant Protein ◽  
Multivesicular Bodies ◽  
Type I ◽  
Type Ii Cells ◽  
Secretory Product ◽  
Type Ii ◽  
Rat Lung ◽  
Adult Rat

We investigated the cellular and subcellular sites of metabolism of the 72,000 dalton protein of pulmonary surfactant in order to provide insights into mechanisms of synthesis, intracellular assembly, and intraalveolar metabolism of this phospholipid-rich secretory product. Surfactant (approximately 90% lipid, 10% protein by weight) was purified by density gradient centrifugation of material obtained by lavaging rat lungs. The purified material was used to generate an antiserum from which a specific antibody was obtained by affinity chromatography. A horseradish peroxidase-labeled Fab was used to localize the antigen in rat lung. The antibody labeled the rough endoplasmic reticulum and Golgi apparatus of type II cells only. Some multivesicular bodies in type II cells were also labeled, but whether the antigen was present in lamellar bodies was uncertain. Phagosomes of alveolar macrophages were labeled as were similar inclusions in type I cells. Using indirect immunocytochemistry we determined that the labeling of alveolar cell surfaces does not represent the presence of a continuous layer of secreted surfactant. These results suggest that only the type II cell synthesizes surfactant protein and than mainly alveolar macrophages participate in its catabolism. The initial intracellular site of the association of protein with lipid may be multivesicular bodies as suggested previously by others.

scholarly journals Differences in basement membrane-associated microdomains of type I and type II pneumocytes in the rat and rabbit lung.

1984 ◽  
Vol 32 (8) ◽  
pp. 827-833 ◽  
Author(s):  
P L Sannes
Keyword(s):  
Basement Membrane ◽  
Basement Membranes ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Sulfate Ester ◽  
Pulmonary Alveoli ◽  
Type I Cells ◽  
Type Ii Pneumocytes ◽  
I Cells

The basement membrane-associated microdomains of type I pneumocytes in rat and rabbit pulmonary alveoli were found to be uniquely different from those of type II pneumocytes in the specific distribution of cytochemically detectable sulfate esters as demonstrated with the high iron diamine (HID) technique at the electron microscopic level. Aldehyde-fixed frozen or Vibratome sections of neonatal and adult lungs were treated with a mixture of the meta and para isomers of N,N-dimethyl-phenylenediamine-HCl in the presence of ferric chloride, which at low pH (1.0) has been previously shown to be highly specific for sulfate esters of glycosaminoglycans and glycoproteins. Reaction product was subsequently enhanced with a thiocarbohydrazide-silver proteinate, postembedding sequence for electron microscopy. Samples of lung parenchyma treated in this fashion were observed to have discrete, electron-dense silver grains associated with the various microanatomical components of pulmonary basement membranes. In the region of the alveolar basement membrane, the lamina rara externa associated with type I cells was observed to contain an abundance of regularly disposed, cytochemically detectable sulfate esters, while the lamina densa and lamina rara interna were diffusely and sparsely reactive by comparison. Quantitatively, 62% of all reactive sites found in the basement membrane region of type I cells were localized in the lamina rara externa. By contrast, the lamina rara externa of type II cells had less than half as many reactive foci indicative of sulfate esters as the same region of type I cell basement membranes. HID-reactive sulfate esters were found evenly distributed within the laminae associated with the basement membrane of type II cells. This cytochemically detectable difference in the sulfate ester composition of basement membrane-associated sulfate ester composition of basement membrane-associated microdomains of type I compared with that of type II pneumocytes may be highly significant when considering known patterns of epithelial renewal in pulmonary alveoli. Since type II cells are known to divide and either remain type II cells or differentiate into type I cells, regional differences in the molecular composition of the alveolar basement membranes and their associated structures may be key determinants of cell-specific processes of cytodifferentiation in the pulmonary alveolus.

scholarly journals Membranoproliferative glomerulonephritis with C3 and intramembranous dense deposits

2013 ◽  
Vol 19 (S4) ◽  
pp. 43-44
Author(s):  
F. Carvalho ◽  
H. Viana ◽  
A.P. Alves de Matos ◽  
M. Amoedo
Keyword(s):  
Basement Membrane ◽  
Membranoproliferative Glomerulonephritis ◽  
Correct Diagnosis ◽  
Type I ◽  
Type Ii ◽  
C3 Nephritic Factor ◽  
Dense Deposit ◽  
Dense Deposits ◽  
Capillary Walls ◽  
Mild Renal Insufficiency

Membranoproliferative glomerulonephritis (MPGN) encompasses 7 to 10% of all biopsied glomerulonephritis. They are divided in: MPGN type I; MPGN type II and MPGN type III, being primary or secondary. MPGN type I are the most frequent, MPGN types II and III are very rare and difficult to diagnose without clinical and morphologic findings integration. MPGN type II or Dense Deposit Disease has a varied morphologic appearance with a few numbers of cases showing a membranoproliferative pattern by Light microscopy (LM). Electron microscopy (EM) is pivotal to confirm the diagnosis.We present a case of 35 years old man, with nephrotic proteinuria and mild renal insufficiency since 2 years. The only relevant clinical data is facial lipodystrophy. Complement 3 (C3) was low and C3 nephritic factor negative. There were not other relevant abnormalities. Renal biopsy was fixed in buffered formaldehyde 10% and performed for LM. The frozen fragment, prepared for observation by fluorescence microscopy - immunofluorescence (IMF) -, was prepared to be stained with florescent anti-serums, against immunoglobulines (IgG, IgA and IgM) and complement factors (C3, C4, and C1q). EM was later done on tissue formaldehyde fixed reprocessed from paraffin-embebbed for LM, because there was no tissue fragment fixed in glutaraldehyde.LM showed variable endocapillary hypercelullarity, with neutrophils infiltration. Capillary walls were thickened due to the deposition of elongate and ribbon-like deposits. Few double contours were visible (Figure 1a). IMF demonstrated the presence of C3 deposits in the capillary walls and mesangium (Figure 1b). EM confirmed the presence of an intramembranous dense deposit along basement membrane which was thickened (Figure 1c). LM and IMF findings favored the diagnosis of MPGN type II with C3 deposits and thickening of basement membrane. Nevertheless EM was essential to confirm intramembranous unequivocally dense deposits.MPGN type II is a rare glomerulonephritis mediated by complement deregulation. The integration of clinical and morphologic findings is essential to get a correct diagnosis. In this setting EM is highly distinctive and required for a definitive diagnosis.

Mechanical Properties of Basement Membrane

Physiology ◽  
1995 ◽  
Vol 10 (1) ◽  
pp. 30-35 ◽  
Author(s):  
LW Welling ◽  
MT Zupka ◽  
DJ Welling
Keyword(s):  
Mechanical Properties ◽  
Basement Membrane ◽  
Elastic Properties ◽  
Safety Margin ◽  
Basement Membranes ◽  
Alveolar Wall ◽  
Renal Tubules ◽  
Young’S Moduli

Basement membranes from renal tubules, capillaries, venules, and pulmonary alveolar wall all have remarkably similar elastic properties and Young's moduli. Strength and safety margin, however, are far smaller in the alveolar wall, perhaps as a result of its complexity of design.

scholarly journals Ultrastructural localization of the major components of the extracellular matrix in normal rat nerve.

1992 ◽  
Vol 40 (6) ◽  
pp. 859-868 ◽  
Author(s):  
P Lorimier ◽  
P Mezin ◽  
F Labat Moleur ◽  
N Pinel ◽  
S Peyrol ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Peripheral Nerve ◽  
Ultrastructural Localization ◽  
Basement Membranes ◽  
Type I ◽  
Immunoperoxidase Method ◽  
Adult Rat ◽  
Normal Rat ◽  
Rat Nerve ◽  
Fibronectin Type

In this study we determined the ultrastructural distribution of the various components of the extracellular matrix (laminin, fibronectin, Type I, III, and IV collagens) of the normal peripheral nerve in adult rat. The localization of these macromolecules was investigated in basement membranes as well as in different areas of epi-, peri-, and endoneurium, by use of a pre-embedding immunoperoxidase method.

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