Lendrum's Chromotrope 2R
for eosinophils

Solutions

Mayer's hemalum or similar

Carbol Chromotrope
Chromotrope 2R	0.5	g
Phenol	1	g
Distilled water	100	mL

Preparation

Place the phenol in an Erlenmeyer flask and melt it under hot water through the glass. Add the chromotrope 2R and mix well into a sludge. Add the water and mix well. Filter before use.

Tissue sample
5µ paraffin sections of neutral buffered formalin fixed tissue are suitable. Other fixatives are likely to be satisfactory.

Method

1. Bring sections to water via xylene and ethanol.
2. Stain nuclei with Mayer's hemalum and blue.
3. Place in the staining solution for 30 minutes.
4. Wash well with tap water.
5. Dehydrate with ethanol.
6. Clear with xylene and mount with a resinous medium.

Expected results

• Nuclei  –  blue
• Eosinophil granules  –  bright red
• Erythrocytes  –  may be lightly stained
• Paneth cell granules  –  may be brownish
• Enterocromaffin granules  –  may be brownish

Notes

1. The basis of this method is difficult to rationalise. Phenol is acidic and thus lowers the pH. This is often used as the basis for explaining the method, but usually an acid dye stains all basic components of the tissue (muscle, cytoplasm, collagen) intensely when applied at an acid pH. While eosinophils are intensely stained with this technique, other components that would usually stain with an acidified acid dye are not. Phenol can behave like this but the mechanism has not been satisfactorily explained and remains an enigma.

 

Reference
Histological demonstration techniques, (1974))
Cook, H C.
Butterworths, London, England.

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