Freeze Substitution Protocol
Freeze Substitution Protocol - Related Videos
09:17
Scanning Transmission Electron Microscopy Tomography in Virology: 3D Imaging of High-pressure Frozen, Freeze-substituted Samples
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2025
This video protocol illustrates how to perform scanning transmission electron microscopy tomography of virological specimens. For optimal outcomes, samples are prepared by high-pressure freezing and subsequent freeze substitution.
12:52
Tandem High-pressure Freezing and Quick Freeze Substitution of Plant Tissues for Transmission Electron Microscopy
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Cited by 20 •
2014
Obtaining high-quality transmission electron microscopy images is challenging, especially in the case of plant cells, which have abundant large water-filled vacuoles and aerated spaces. Tandem high-pressure freezing and quick freeze substitution greatly reduce preparation time of plant samples for TEM while producing samples with excellent ultrastructural preservation.
14:21
Nucleophilic Substitution
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2023
Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA Nucleophilic substitution reactions are among the most fundamental topics covered in organic chemistry. A nucleophilic substitution reaction is one where a nucleophile (electron-rich Lewis base) replaces a leaving group from a carbon atom. SN1 (S = Substitution, N = Nucleophilic, 1 = first-order kinetics) SN2 (S = Substitution, N = Nucleophilic, 2 = second-order kinetics) This video will help to...
07:30
Protocol for Producing Three-Dimensional Infrared Video of Freezing in Plants
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Cited by 1 •
2018
Here, we present a protocol to image a strawberry plant freezing in 3 dimensions. Two infrared cameras positioned at slightly different angles are used to produce a red-blue anaglyph video to observe the freezing of the plant in 3 dimensions.
10:14
Object Substitution Masking
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2023
Source: Laboratory of Jonathan Flombaum—Johns Hopkins University Visual masking is a term used by perceptual scientists to refer to a wide range of phenomena in which in an image is presented but not perceived by an observer because of the presentation of a second image. There are several different kinds of masking, many of them relatively intuitive and unsurprising. But one surprising and important type of masking is called Object Substitution Masking. It has been a focus of research in vision...
FAQs
During Freeze substitution, the specimen remains frozen while a chilled dehydrating solvent, such as acetone or methanol, gradually removes ice. This low-temperature exchange replaces frozen water without first exposing the sample to conventional dehydration conditions. The controlled sequence helps preserve membranes, macromolecular distributions, and fine ultrastructure for subsequent microscopy.
Fixatives can stabilize cellular components during the low-temperature solvent exchange, helping structures remain in place as ice is removed. Their inclusion is therefore part of the preservation strategy rather than a separate imaging step. Stabilization supports later sectioning and microscopy, particularly when researchers need cellular organization or molecular distributions to remain faithful to the original specimen.
The method addresses distortion and extraction that can occur during conventional dehydration. Because ice is removed while the specimen remains at low temperature, biological structures can be preserved with less disruption. This is important when microscopy must reveal membranes, fine ultrastructure, or macromolecular distributions, since these features can be affected by processing-related structural changes.
After freezing, the specimen is placed in chilled acetone or methanol, where ice is gradually removed and fixatives may stabilize cellular components. The sample is then warmed, infiltrated, and embedded before sectioning. This sequence carries the specimen from cryogenic preservation to a sectionable preparation while retaining structures needed for microscopy.
The critical materials and condition are a frozen specimen, chilled organic solvent, and a controlled transition from low temperature to warming. Acetone or methanol serves as the dehydrating solvent, while optional fixatives stabilize cellular components. Subsequent infiltration and embedding prepare the preserved specimen for sectioning and microscopy.
The protocol is especially useful for electron microscopy and immunolabeling, where faithful preservation supports interpretation of cellular organization and molecular distributions. It can also aid studies of pathogens and interactions between biological components. By limiting structural distortion and extraction, the preparation helps investigators examine fine biological relationships that depend on preserved ultrastructure.