Electron microscopic studies membranes

Light and electron microscopic studies were performed on the synovial membranes (E2) of patients with HIV associated arthropathy. An immunoperoxidase technique with the use of monoclonal antibodies against CD4, CD8, B, and DR lymphocytes and HIV p 24 antigen was also used. Mild to moderate nonspecific proliferative changes and increased vascularity of the subsynovial space were seen. Immunohistochemical staining revealed HIV p 24 positive staining cells of the synovial lining layer and the mononuclear cells of the subsynovial space, CD4, CD8 with predominance of CD8, B, and DR cells were also present. 

Ceynowa performed electron microscopic studies of 60—80 nm thick microtomed Nafion 125 membranes that were converted, for the purpose of affecting electron density contrast, to the Pb2+ form, and all of the excess cations and co-ions were removed. It is the heavy metal that provides electron density contrast between the phase in which it resides and the surrounding phase. These membranes were then exposed to ethanol and 1,2-epoxypropane, although these solvents would not have remained in the samples under the vacuum in the microscope column. The micrographs consisted of uniformly distributed points that were presumed to be ion clusters that were 3—6 nm in diameter. 

An important observation is that certain viruses preferentially bud at different poles of their host cells. In MDCK-cell monolayers, VSV buds exclusively from the basal, or lateral, plasma membranes, and contains sialylated glycoproteins, whereas influenza virus buds exclusively from the apical plasma-membrane, and lacks neuraminic acid. The question arises as to whether glycosylation of viral glycoproteins is needed in order to determine the site of budding. An electron-microscope study revealed that polarity in the maturation sites of these viruses was maintained under conditions of inhibition of glycosyla-... 

Most electron microscopic studies of BBB endothelial cells suggest the presence of relatively few observable endocytic vesicles in the cytoplasm of these cells compared with other endothelia. For example, the BBB contains only a fifth to a sixth of the endocytic profiles seen in muscle capillary endothelia [54], although they may increase to comparable levels with inflammation of the BBB [55]. However, when a comparison is made of the ability of capillary endothelia in a variety of different tissues to trancytose protein, there is a very poor correlation between the protein permeability of a microvessel and the number of observable endocytic profiles [54]. Brain capillary endothelia are very thin cells, the luminal and ablum-inal membranes only being separated by some 500 nm or less (5000 A), and caveoli are 50-80 nm in diameter and thus the events of transcytosis may be difficult to capture within the cell using conventional electron microscopical techniques. 

Transmission electron microscope studies have shown that the organic interlamellar membranes have a lamellar structure (Figure 16(a), (b)). This structure varies according to the taxa. Some fenestrations or holes have been described, and they have been considered to favor the passage of fluid substances needed for the minerahzing process. The decalcificafion process of the nacreous layer, and later all the mollusc layers and invertebrate tests, has shown... 

Electron microscopic studies by George Palade and Fritjof Sjostrand revealed that mitochondria have two membrane systems an outer membrane and an extensive, highly folded inner membrane. The inner membrane is folded into a series of internal ridges called cristae. Hence, there are two compartments in mitochondria (1) the intermembrane space between the outer and the inner membranes and (2) the matrix, which is hounded by the inner membrane (Figure 18.3). Oxidative phosphorylation takes place in the inner mitochondrial membrane, in contrast with most of the reactions of the citric acid cycle and fatty acid oxidation, which take place in the matrix. 

Nielsen S. Endocytosis in renal proximal tubules. Experimental electron microscopical studies of protein absorption and membrane traffic in isolated, in vitro perfused proximal tubules. Dan Med Bull 1994 41 243-63. 

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