| The most common stain used throughout the world as the basic morphology preparation is the
"H&E" or, to give it its full name, the Haematoxylin and Eosin stain. Haematoxylin is a
natural dye extracted from trees. It is a basic dye and therefore binds with acidic tissue
components. This means, basically, that it will stain cell nuclei which contain DNA and RNA,
the nucleic acids. Eosin on the other hand, is an acidic dye and binds with basic tissue
components including the cell membranes and organelles. On the right you can see a few slides
which have been stained using the H&E method. Notice that the cumulative effect of red/blue
staining at a macroscopic level is purple. (Note: I have smudged out the case numbers on
these slides for privacy reasons.) |
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| Other staining methods are used to demonstrate other substances within
the block or other cellular components. Here you can see a microscopic view of fungal hyphae
stained by the PAS (Periodic Acid, Schiff) reaction. |
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| Here is a slide stained by the Giemsa method. If you look closely at the
middle of this gland, you will see some very tiny dark blue flecks. These are the bacterium
Helicobacter Pylori which is involved in many cases of gastric ulcers, and in some cases of
gastric cancer. |
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| Here you can see the connective tissue "Reticulin" - named because of its
net-like appearance. In this picture the reticulin fibres are stained black by silver
impregnation. The red is a counterstain showing the liver cells. |
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| Finally, in this picture you can see liver tissue again. The red dots are
the nuclei of the liver cells and the blue is a positive reaction in the Perls' Prussian Blue
technique for iron. |
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