Freeze-etch studies

Mirgall F., Breipohl W. and Bhatnagar K. (1979). Ultra-structural investigation on the cell membranes of the vomeronasal organ in the rat — a freeze-etching study. Cell Tiss Res 200, 397-408. 

Witchett CE Exposure of dog erythrocytes in vivo to phenylhydrazine and monomethylhy-drazine—a freeze-etch study of erythrocyte damage, p 33. Springfield, VA, US Department of Commerce, NTIS, 1975... 

Kerjaschki, D. and Horandner, H. The development of mouse olfactory vesicles and their cell contacts A freeze-etching study. J. Ultrastruct. Res.. 1976, 5I+, l+20-l+l+l. ... 

Freeze-etch preparations of sterol-containing liposomes or erythrocyte membranes treated with amphotericin B did not reveal pits [256]. The postulated amphotericin B—sterol pores would be too small to be seen by this technique. However, freeze-etch studies of amphotericin B-treated plasma membranes isolated from Epidermophyton floccosum [261 ], a fungus pathogenic to man, has revealed depressions (or craters) and aggregates of membrane-associated particles (85 A in diameter). The areas of disruption did not traverse the membrane. 

Freeze-etching studies on frozen aqueous suspensions of polyes-tyrene microspheres (Park and Branton, 1968) exemplify random distorting effects of the microtome knife impact on the shape and position of ice-embedded particles. 

Verkleij, A.J., Zwaal, R.F., Roelofsen, B., Comfurius, P., KasteUjn, D. and van Deenen, L.L.M., 1973, The asymmetric distribution ofphosphoUpids in the human red cell membrane. A combined study using phospholipases and freeze-etch electron microscopy. 

These results were confirmed by an electron microscopy study using a freeze-etching replication technique (1 ). The aim of this technique was to conserve the real gel structure by blocking any diffusion processes in the gel sample by the freezing action of liquid nitrogen. The three-dimensional network is then recovered... 

The interpretation of electron micrographs is often hampered by artefacts introduced during the sample preparation and etching. The technique of freeze etching is almost imperative for the study of swollen networks, where the structure depends often on the presence of diluent (see Chapter II, Section 3 and 4). 

Various electron microscopy techniques have been used to study the structures of whippable emulsions such as normal and cryo-scanning electron microscopy or transmission electron microscopy using various preparation methods such as freeze fracturing, freeze etching, etc. The literature is quite extensive, and only a few important papers will be discussed in this chapter. 

The most thorough study of the formation of artificial casein micelles is that of Schmidt and co-workers (1977 1979 Schmidt and Koops, 1977 Schmidt and Both, 1982 Schmidt and Poll, 1989), who not only studied the properties of the casein aggregates but also attempted to relate them to the solution conditions under which they were formed. In the precipitation of calcium phosphate from solution, the means by which solutions are mixed together is of crucial importance Schmidt et al. (1977) described a method in which four solutions were pumped simultaneously into a reaction vessel while keeping the pH constant. As a result of careful, slow mixing, the reproducibility of the size distributions of particles, measured by electron microscopy on freeze-fractured and freeze-etched specimens, was very good. In the first series of experiments, the objective was to produce milk like concentrations of the most important ions while... 

Schmidt, D.G., Buchheim, W., Koops, J. 1971. An electron-microscopic study of fat-protein complexes in evaporated milk, using the freeze-etching technique. Neth. Milk Dairy J. 25, 200-216. 

Bailey, A. and Bisalputra, T., 1970. A preliminary account of the application of thinsec-tioning, freeze-etching, and scanning electron microscopy to the study of coralline algae. Phycologia, 9 83—101. 

Menco BP. 1984. Ciliated and microvillous structures of rat olfactory and nasal respiratory epithelia. A study using ultra-rapid cryo-fixation foUowed by freeze-substitution or freeze-etching. CeU Tissue Res 235 225-241. 

Many approaches have been used to study membrane structure electron microscopy of freeze-fractured and freeze-etched preparations, localization of antigens using ferritin-labelled antibodies, crossed immunoelectrophoresis, chemical probes and cross-linking agents, and instrumental techniques such as nuclear magnetic resonance and electron spin resonance spectroscopy. Their contribution to our present understanding of membrane anatomy has been reviewed by Salton and Owen [24]. 

Freeze etching of stelar tissue in Zea mays roots has demonstrated the association of globular complexes with the ends of nascent microfibrils. The results support a model for the synthesis of cellulose in which an enzyme complex in the granule adds D-glucopyranosyl residues to the developing end of a microfibril. The ultrastructure of the cellulosic network of the primary cell wall of pine wood and its development during the formation of tracheids have been studied by electron microscopy. ... 

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