Dyes Flashcards
Hematoxylin and Eosin
- Hematoxylin stains cellular regions rich in basophilic macromolecules (DNA or RNA) a purplish blue or blue-black color.
- It is the most common stain for demonstrating cell nuclei and cytoplasm rich in rough ER.
- Usually used as the contrasting “counterstain” with hematoxylin, eosin is an acidic stain that binds to basic macromolecules such as collagen and most cytoplasmic proteins, especially those of mitochondria.
- Eosin stains regions rich in such structures a pinkish red color.
- Tissue sections showing only structures with shades of purple and pink are stained with H&E.
Pararosaniline-Toluidine Blue
- This dye combination stains chromatin shades of purple and cytoplasm and collagen a lighter violet.
- These stains penetrate plastic sections more readily than H&E and are used here primarily with acrylic resin-embedded sections to provide better detail of cell and tissue structures.
- Toluidine blue is also commonly used for differential staining of cellular components, particularly cytoplasmic granules.
Mallory Trichrome
This procedure employs a combination of stains applied in series which results in
- nuclei staining purple
- cytoplasm, keratin, and erythrocytes staining bright red or orange
- collagen bright or light blue.
Mallory trichrome is particularly useful in demonstrating cells and small blood vessels of connective tissue.
Similar stains, such as Masson trichrome and Gomori trichrome, yield comparable results except that collagen stains blue-green or green.
Picro-Sirius-Hematoxylin
The dye Sirius red in a solution of picric acid stains
- collagen red
- cytoplasm a lighter violet or pink,
- nuclei purple
if first stained with hematoxylin. Under the polarizing microscope, collagen stained with picrosirius red is birefringent and can be detected specifically.
Periodic Acid–schiff Reaction
- This histochemical procedure stains complex carbohydrate-containing cell components, which become magenta (shades of purplish pink).
- PAS is commonly used to demonstrate cells filled with
- Mucin granules
- Glycogen deposits
- The glycocalyx.
Wright-Giemsa Stain
- These are two similar combinations of stains that are widely used on fixed cells of blood or bone marrow smears to demonstrate types of blood cells.
- Granules in leukocytes are seen to have differential affinity for the stain components. Nuclei stain purple and erythrocytes stain uniformly pink or pinkish orange.
Silver Or Gold Stains
- Various procedures employing solutions of silver or gold salts have been developed to demonstrate filamentous structures in neurons and fibers of reticulin (type III collagen).
- By these “metal impregnation” techniques these filaments stain dark brown or black. Such stains have been largely replaced now by immunohistochemical procedures.
Stains For Lipid
- When special preparation techniques are used to retain lipids of cells, such as in frozen sections, lipophilic dyes are used to demonstrate lipid droplets and myelin.
- Oil red O and Sudan black stain lipid-rich structures as their names suggest. Osmium tetroxide (osmic acid), which is used as a fixative for TEM, is reduced to a black substance by unsaturated fatty acids and is also used to demonstrate lipids.
Stains For Elastin
- Several staining methods have been developed to distinguish elastic structures from collagen, most of which stain the elastin-rich structures brown or shades of purple.
- Examples of such stains are:
- ** Weigert’s resorcin fuchsin**
- Aldehyde fuchsin
- Orcein Van Gieson stains.
Other Common Stains
Many basic aniline dyes, including azures, cresyl violet, brilliant cresyl blue, luxol fast blue, and light green, are used because of the permanence and brightness of the colors they impart to cellular and extracellular structures in paraffin sections. Many such stains were initially developed for use in the textile industry.
