A comparative study of fixation and dehydration techniques for the preservation of conidial structures in fungi for SEM

1987 ◽  
Vol 45 ◽  
pp. 982-983
Author(s):  
Richard E. Edelmann ◽  
Margaret E. Hogan
Keyword(s):  
Electron Microscopy ◽  
Freeze Drying ◽  
List Type ◽  
Type Number ◽  
Improved Method ◽  
Physical Damage ◽  
Air Drying ◽  
Reproductive Structures ◽  
Critical Point Drying ◽  
Scanning Electron

Conventional preparative techniques for biological specimens For scanning electron microscopy (SEM), when used for Fungal specimens, involve immersion in fixation and dehydration solutions. This often results in physical damage to delicate reproductive structures. Attempts at eliminating this damage using OsO4 vapors as a fixative, followed by air drying, may also produce less than optimal results.In order to devise an improved method for preparing fungal specimens, several genera were selected for their very delicate aerial conidial structures, and were prepared using six different procedures. The various protocols were as Follows:1)Immersion Fixation in 1% paraformaldehyde, 2.5% glutaraldehyde in H2O, post-fixation with 2% OsO4, and critical point drying2)2% OsO4 (in H2O) vapor fixation and air drying3)2% OsO4 (in H2O) vapor fixation and freeze drying4)Powdered paraformaldehyde in a 6% relative humidity atmosphere vapor fixation and air drying5)Aqueous 5% paraformaldehyde/8% glutaraldehyde vapor fixation, and air drying6)Aqueous 5% paraFormaldehyde/8% glutaraldehyde vapor fixation, and freeze drying

Preservation of Plant Cell Surfaces For Scanning Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 472-473
Author(s):  
Linda M. Sicko ◽  
Thomas E. Jensen
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Critical Point ◽  
Filter Paper ◽  
Freeze Drying ◽  
Cell Surfaces ◽  
Air Drying ◽  
Popular Method ◽  
Critical Point Drying ◽  
Scanning Electron

The use of critical point drying is rapidly becoming a popular method of preparing biological samples for scanning electron microscopy. The procedure is rapid, and produces consistent results with a variety of samples. The preservation of surface details is much greater than that of air drying, and the procedure is less complicated than that of freeze drying. This paper will present results comparing conventional air-drying of plant specimens to critical point drying, both of fixed and unfixed material. The preservation of delicate structures which are easily damaged in processing and the use of filter paper as a vehicle for drying will be discussed.

Simple desiccation method for SEM using dimethoxypropane

1992 ◽  
Vol 50 (1) ◽  
pp. 760-761
Author(s):  
Frantíšek Weyda
Keyword(s):  
Electron Microscopy ◽  
Freeze Drying ◽  
Simple Procedure ◽  
Aqueous Suspension ◽  
Freeze Substitution ◽  
Biological Specimen ◽  
Air Drying ◽  
Biological Objects ◽  
Critical Point Drying ◽  
Scanning Electron

A number of techniques such as critical point drying (the most commonly used method of drying cells and tissues), freeze-drying or freeze-substitution are available to process various tissues preparations for scanning electron microscopy (SEM). Those techniques are more or less complicated (depending also on expensive equipments) and time consuming. While more simple air-drying from aqueous suspension or organic solvents can be used for some rigid biological specimen, it is generally not satisfactory for most tissues and biological objects. On the opposite, rapid and simple procedure using hexamethyldisilazane (HMDS) and air drying has been successfully applied to insect and mite tissues without observable artifacts. We have developed similar simple and rapid method using dimethoxypropane (DMP) and air drying. DMP has previously been used for chemical dehydration of tissues.

A technique for preparing Beauveria spp. for scanning electron microscopy

1980 ◽  
Vol 58 (15) ◽  
pp. 1700-1703 ◽  
Author(s):  
E. C. Quattlebaum ◽  
G. R. Carner
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Freeze Drying ◽  
Osmium Tetroxide ◽  
Air Drying ◽  
Preparation Methods ◽  
Critical Point Drying ◽  
Scanning Electron

Vapor fixation for 96 h with 1% osmium tetroxide (OsO4) and 3–4 days air drying produced distortion-free specimens of Beauveria spp. for examination with the scanning electron microscope. A combination of 4 h OsO4 vapor fixation and freeze-drying also reduced disruption satisfactorily but specimens were not as well preserved as with the first method. Preparation methods that were ineffective in preventing collapse of hydrophilic structures were Cling Free® sprayed on specimens prior to examination, freeze-drying, critical-point drying (of unfixed material), and vapor fixation with glutaraldehyde.

scholarly journals How to Prepare Biological Samples and Live Tissues for Scanning Electron Microscopy (SEM)

2014 ◽  
Vol 3 (2) ◽  
pp. 63-80
Author(s):  
Abolfazl Mehdizadeh Kashi ◽  
Kobra Tahemanesh ◽  
Shahla Chaichian ◽  
Mohammad Taghi Joghataei ◽  
Fateme Moradi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Freeze Drying ◽  
Specimen Preparation ◽  
Imaging Method ◽  
Tissue Preservation ◽  
Chemical Fixation ◽  
Biological Specimen ◽  
Air Drying ◽  
Critical Point Drying ◽  
Scanning Electron

In this article we review the application and procedures involved in scanning electron microscope (SEM) to observe biological and live tissues through using SEM at high resolution. We discuss practical methods for optimizing tissue preservation to achieve the two principal goals of biological specimen preparation: (a) preserving biological structures as close to their living configuration as possible, and (b) rendering them visible with the desired imaging method. We also review and discuss the relative merits of different fixing (chemical fixation and cryofixation), drying (air-drying, critical point-drying, freeze-drying and chemical-drying) and coating procedures of biological specimens with metals to facilitate visualization in the SEM.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

Criteria for the evaluation of low-temperature Scanning Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 902-903
Author(s):  
Alan Beckett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Conformational Changes ◽  
Chemical Vapour ◽  
List Type ◽  
Dimensional Changes ◽  
Critical Point Drying ◽  
Temperature Scanning ◽  
Scanning Electron

Low temperature scanning electron microscopy (LTSEM) has been evaluated with special reference to its application to the study of morphology and development in microorganisms. A number of criteria have been considered and have proved valuable in assessing the standard of results achieved. To further aid our understanding of these results, it has been necessary to compare those obtained by LTSEM with those from more conventional preparatory procedures such as 1) chemical fixation, dehydration and critical point-drying; 2) freeze-drying with or without chemical vapour fixation before hand.The criteria used for assessing LTSEM for the above purposes are as follows: 1)Specimen immobilization and stabilization2)General preservation of external morphology3)General preservation of internal morphology4)Exposure to solvents5)Overall dimensional changes6)Cell surface texture7)Differential conformational changes8)Etching frozen-hydrated material9)Beam damage10)Specimen resolution11)Specimen life

Alternative Method of Rapid Drying Vascular Specimens for Scanning Electron Microscopy

2003 ◽  
Vol 10 (2) ◽  
pp. 285-287 ◽  
Author(s):  
DáŠa Slížová ◽  
Otakar Krs ◽  
Blanka PospíŠilová
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Micrographs ◽  
Low Cost ◽  
High Rate ◽  
Drying Methods ◽  
Scanning Electron Micrographs ◽  
Air Drying ◽  
Critical Point Drying ◽  
Scanning Electron

Purpose: To report the use of hexamethyldisilazane (HMDS) as an alternative to critical point drying for preparing stented canine peripheral vessels for scanning electron microscopy (SEM). Technique: Vascular specimens were fixed in 4% formaldehyde overnight, dehydrated in a graded ethanol series, followed by immersion in 100% hexamethyldisilazane. After air drying, the specimens were mounted on stainless steel stubs, coated with gold, and examined in the SEM. The electron micrographs were of high quality, showing the layers of the vascular wall and the incorporated stent covered by a neointimal layer. The micrographs were comparable to corresponding histological sections, but detailed endothelial patterns were more visible. Conclusions: HMDS treatment and subsequent air drying provides good quality scanning electron micrographs that reveal both endothelial patterns and the layered architecture of stented vessels. The disadvantage of HMDS drying may be a shrinkage and distortion similar to other drying agents. Ease of handling, low cost, and a high rate of success are advantages that favor HMDS desiccation over other drying methods.

Delicate Botanical Specimens Preserved for Scanning Electron Microscopy by Critical Point Drying

1971 ◽  
Vol 29 ◽  
pp. 450-451
Author(s):  
Arthur L. Cohen ◽  
Gerald E. Garner
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Critical Point ◽  
Freeze Drying ◽  
Animal Cell ◽  
Pollen Grains ◽  
Scanning Electron Micrographs ◽  
Animal Cells ◽  
Critical Point Drying ◽  
Scanning Electron

The surface forms and structures of animal cells have been strikingly preserved for scanning electron microscopy by freeze-drying and by critical point drying both by the method with CO2 used as the transitional fluid and the later procedure which uses a fluorocarbon (Freon 13) as a medium for the transition from the liquid to the gaseous environment. Freeze-drying is often prolonged (5-12 hours as compared with an hour or less by the critical point method) and in our experience with mold cultures on agar, the substrate shrivels and cracks and hyphal filaments are distorted.Despite, and possibly because of a flexible but inelastic cell wall, plant cells often show greater distortion than do animal cells after evaporative drying or replacement dehydration for mixrotechnical work. The animal cell membrane can contract more or less uniformly on drying - as shown by the numerous micrographs of well-preserved erythrocytes, while plant cell walls often crumple. The many scanning electron micrographs of partially collapsed pollen grains bear witness to this fact.

Scanning Electron Microscopy of Ethanol Infiltrated Freeze-Fractured Cell Pellets

1974 ◽  
Vol 32 ◽  
pp. 98-99
Author(s):  
William G. Henk ◽  
Ben O. Spurlock
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Critical Point ◽  
Freeze Drying ◽  
Cultured Cells ◽  
Resolving Power ◽  
Ice Crystal ◽  
Internal Structures ◽  
Critical Point Drying ◽  
Scanning Electron

The increased depth of focus and superior resolving power of the scanning electron microscope provide advantages over the light microscope in viewing the external morphology of cultured cells and protists. Internal structures have, however, proved more difficult to observe. Freeze drying adequately preserves surface structures but results in poorly preserved cytoplasmic elements due to ice crystal damage. Critical point drying results in good preservation of both surface and cytoplasmic fine structure. Attempts to cut or break critical point dried material, however, result in plastic deformation of the cells. Humphreys, et al, recently introduced freeze fracturing of ethanol infiltrated tissues for biological scanning electron microscopy. We have modified and applied their technique and obtained similar results with Paramecium sp. obtained from mass cultures.

A Study on the Occurrence of Gold in Unoxidized Carlin-Type Ores in China Using AEM, SEM-EDX and SXRF

1990 ◽  
Vol 48 (2) ◽  
pp. 414-415
Author(s):  
Liu Yongkang ◽  
Liu Shirong ◽  
Wan Guangquan ◽  
Zhou Lindi ◽  
Li Jilian ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Gold Mineralization ◽  
Analytical Electron Microscopy ◽  
List Type ◽  
Type Number ◽  
X Ray ◽  
Combined Use ◽  
Analytical Electron ◽  
Scanning Electron ◽  
Gold Bearing

The knowledge about the occurrence of gold is essential both to the explanation for the genesis of gold mineralization in its deposits and to the evaluation and exploration or even smelt process of its ores. It has been well known that the gold occurrence in the Carlin-type ores still remains a difficult question to be answered because of the tiny scale of its locality and its very low content.This paper reports the results of our analysis on some gold bearing minerals in the Carlin-type ores discovered during recent years in China with combined use of analytical electron microscopy (AEM), scanning electron microscopy-energy dispersive X ray spectrometry (SEM-EDX) and synchrotron X ray flourescence analysis (SXRF) techniques as following:(1) Some gold occurred as submicron size grains in the ores (see Photo 1-4 and Figure 1-3) with grain size generally less than 0.2 micron.(2) It has been found by AEM and SEM-EDX observation and SXRF analysis that gold occurred as micrograins embedded in the boundaries of clay or quartz minerals rather than, as said, entered the lattice or adhered as a covering film to the surface of clay minerals (see Figure 4).

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