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At least 793 records · Page 44Linked to original sources
PubMed1975

Scanning and transmission electron microscopy of calcified tissues.

Some recent innovations have been utilized to extend studies of the structure of calcified tissues on the ultra- and microstructural levels of organization. The introduction of hydrazine as a replacement for the conventionally used ethylene diamine to deproteinize calcified tissue samples has resulted in the acquisition of previously unobtainable information about the mineral phase as it exists in situ. This enables inference of mineral-organic interrelationships when coupled with the EDTA demineralization technique used to study collagen fiber frameworks. In addition, a method for obtaining whole single osteons and separating them into lamellar constituents permits observations of the collagen-apatite orientation within successive lamellae of compact Haversian bone. The use of the structural information derived to develop a fiber-reinforced model of compact bone as a composite material is outlined and discussed.

Bone and Bones↗
PubMed1979

Studies on cell surface conformation following injury. II. Scanning and transmission electron microscopy of cell surface changes following anoxic injury in Ehrlich ascites tumor cells.

Exposure of Ehrlich ascites tumor cells to anoxia resulted in rapid and characteristic conformational changes of cell surface topography. Combined scanning and transmission E/M studies revealed rapid alterations including simplification of the cell surface configuration with disappearance of microvilli which were replaced with formation of blebs and recesses at the cell periphery. These surface changes were accompanied by characteristic organelle alterations inside the cells which in this and other cellular systems have been shown to be reversible. Later, the cell surface topography became smoother and monotonic with small blebs and cribriform invaginations in addition to larger eruptions of the cell periphery. Combined transmission E/M studies revealed fragmentation of cellular membrane systems and lysis of organelles indicating the irreversible phase of anoxic injury. The rapid conformational surface changes encountered in Ehrlich ascites tumor cells following anoxia suggest the important role of the plasma membrane and its unfolding as a virtually instantaneous response of the cells to this injury.

Animals↗
PubMed1990

[A method for the chemical treatment of cells for the purpose of the subsequent study of the same cell culture preparation by light, scanning and transmission electron microscopy].

Cells cultured on transparent conductive substrates (glass coated with indium oxide) were fixed with aldehyde and osmium tetroxide and then treated with tannic acid, uranyl acetate and lead citrate. The same cell culture preparation could be sequentially studied by light microscopy (in water immersed condition), SEM (after dehydration and critical point drying) and TEM (after embedding in an epoxy resin). This method ensures the preservation of intact cell morphology, cell surface topography and intracellular structures. The treatments used render the cells conductivity and permit to carry out successfully SEM of uncoated cells cultured on conductive substrates. This method also provides a higher contrast of TEM images.

Animals↗
PubMed1990

[The use of freeze fracturing in combination with light, scanning and transmission electron microscopy for studying the structure of the normal and atherosclerotically altered human aortic intima].

Three-dimensional network of smooth muscle cells (SMC) with processes was found in the subendothelial intima of human aorta. The cells were connected with each other through gap junctions. In the direction from the media to the endothelium the number of plasma membrane caveolae increased, their distribution becoming more random. In the fatty streak, the integrity of cellular network was seen destroyed. In the extracellular matrix multilamellar ball-like structures containing large intramembranous particles appeared. In the fibrous plaque, SMCs are completely isolated by connective tissue fibres.

Aorta, Thoracic↗
PubMed1990

Rhodamine 123 phototoxicity in laser-irradiated MGH-U1 human carcinoma cells studied in vitro by electron microscopy and confocal laser scanning microscopy.

Rhodamine 123 (R123) is a permeant, cationic, fluorescent dye that localizes preferentially within mitochondria of living carcinoma cells. MGH-U1 human bladder carcinoma cells incubated in vitro with 10 microM R123 for 30 min and then irradiated at 514.5 nm with an argon ion laser underwent selective, phototoxic injury to mitochondria. Ultrastructurally, treatment with R123 plus irradiation with 10 J/cm2 caused selective, progressive mitochondrial alterations consisting of disruption of cristae, vacuolization, swelling, increasing numbers of ring-shaped and angulated mitochondria at 4 to 8 h after irradiation, and obliteration of many mitochondria at 24 to 48 h. Confocal laser scanning microscopy after treatment with R123 plus irradiation with 10 to 30 J/cm2 demonstrated altered uptake and localization of subsequently administered R123, accompanied by striking mitochondrial fragmentation. Irradiation caused a dose-dependent depletion of extractable R123, due to a photosensitized efflux that began immediately and progressed by 4 h after irradiation with 10 to 30 J/cm2; further uptake after reincubation in the presence of R123 was also quantitatively impaired in cells previously irradiated with 30 J/cm2.

Carcinoma, Transitional Cell↗