Progressive vs Regressive H&E Staining. The Differences, Explained
A process used consistently in histopathology labs, H&E (Hematoxylin and Eosin) staining provides histologists and pathologists a highly detailed view of the tissue samples they are examining.
When cell structures such as cytoplasm, nucleus, organelles, and extra-cellular components are precisely stained, the enhanced contrast provides better differentiation of a tissue’s various cellular compartments.
H&E Staining is the most popularly used staining process in histology and histopathology labs.
Staining tissues with various dyes to heighten the contrast of the microscopic images is a standard histological procedure.
H&E staining utilizes two separate dyes: Hematoxylin and Eosin. This stain combination enhances tissue view, as each dye highlights different elements of the tissue being examined and brings to the forefront the biochemical differences of a tissue sample.
- Hematoxylin: This positively charged dye features the reaction of a basic dye and appears as a purple to blue color on a tissue sample. Hematoxylin stain adheres to the DNA and nucleoprotein-holding cell nucleus and also highlights the RNA-containing organelles, including ribosomes and the endoplasmic reticulum
- Eosin: This more acidic and negatively charged dye typically stains tissue components in a red to pink color. Eosin stain adheres to basic tissue structures including the cell walls, the cytoplasm, and extracellular fibers
Through the use of the proper H&E stain, histologists produce important views of normal — and abnormal — cell and tissue characteristics.
Progressive, Modified Progressive, and Regressive H&E Staining: How They Differ
H &E staining processes are classified into types: progressive and regressive.
- Progressive stains allow for a higher result intensity due to a longer staining process.
- Progressive staining utilizes a weaker H&E solution
- The process must be stopped at just the right time in order to achieve the stain’s planned-upon intensity
- Progressive staining does not need differentiation (which is the process of removing excess stain)
- Progressive staining highlights mucin and other noncellular tissue material by the Hematoxylin. Any staining of extracellular tissue components can help better indicate tumors that are well-differentiated.
- Regressive staining comprises a process where the tissue being studied is purposely over-stained until all of the tissue’s components are dye-saturated
- After the Regressive staining is complete, the tissue is “de-stained” until it achieves the desired end-point. This de-staining step is called differentiation
- Most of the time, de-staining is achieved using an acidic solution made up of dilute HCL, or acetic acid in alcohol or in water. After de-staining, the slide is “blued” by rinsing the lens under tap water until blue sections appear on the sample
- When very clear differentiation of tissue elements is required, Regressive staining is preferred by histologists because of the customized stain intensity that results from the process
There is also another type of H&E staining process called Modified Progressive Staining:
- Modified progressive staining is the process in which background staining is removed (rather than removing any excess nuclei staining) by using a mild differentiator
- Just like with Progressive Staining, the differentiator should not be too strong or the nuclei will be stained too pale to properly read
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