Histology Articles
Histological staining involves the use of dyes to highlight specific intra- or extracellular elements within tissue. A vast array of dyes and associated staining protocols exist in use. Each dye is targeted toward different cellular…
Artifacts that appear in stained slides may result from a number of causes including improper fixation, the type of fixative, poor dehydration, improper reagents, or poor microtome sectioning. The presence of a fine black precipitate…
Once embedded, tissues are cut into thin sections ready to be placed on a slide. This is done with a microtome, an apparatus for feeding the blocks past an ultrasharp blade with micron level precision.…
For mechanical support during the sectioning process, tissue must be infiltrated with an embedding medium. The usual embedding media are paraffin for light microscopy and an epoxy resin for EM samples. Paraffins are available that…
The step following dehydration is called “clearing” and consists of replacing the dehydrant with a substance that will be miscible with the embedding medium (paraffin). The term “clearing” comes from the fact that the clearing…
Dehydration is usually carried out by transferring the tissue through solutions of increasing alcohol concentration, until 100% alcohol is reached. Sometimes the first step is a mixture of formalin and alcohol. Other dehydrants can be…
Once fixed, the tissue must be treated to allow the cutting of the thin sections required for viewing under the microscope. The procedures designed to prepare the tissue for sectioning are collectively known as tissue…
The removal of calcium deposits is essential for good embedding procedure. Decalcification is usually carried out between the fixation and processing steps. Bone must obviously be processed in this way, but other tissues may also…
Fixatives are among the most hazardous substances used in life science research. Work with these substances under the hood wearing gloves, lab coat and safety goggles. Formaldehyde is a suspect cancer hazard and a strong…
Fixation protocols are usually straightforward. The tissue is cut to dimensions suited to the rate of penetration of the particular fixative and placed in the fixative solution. The number of factors affecting the fixation process…
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- Working Safely with Fixatives
- The Chemistry of Dyes and Staining
- Suggested procedures for processing fixed tissue
- Staining Procedures
- Sectioning
- Overview of the Paraffin Technique
- Overview of Fixation
- Non-Aldehyde Fixatives
- Mounting Tissue Sections
- Factors Affecting Fixation
- Embedding
- Dehydration
- Decalcifying Tissue for Histological Processing
- Clearing Tissue Sections
- Artifacts in Histologic Sections
- Aldehyde Fixatives