Highman's Congo Red
for Amyloid

Solutions

Mayer’s hemalum

Congo red
congo red	0.5	g
Distilled waterx	50	mL
Ethanol, 100%	50	mL

Alkaline ethanol
Ethanol, 80%	100	mL
Potassium hydroxide	0.2	g

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. Place into congo red solution for 5 minutes or longer.
3. Differentiate in alkaline ethanol (about 5-30 seconds).
4. Wash well with tap water.
5. Stain nuclei with hematoxylin and blue.
6. Dehydrate with ethanol.
7. Clear with xylene and mount with a resinous medium.

Expected results

• Amyloid  –  orange red
• Nuclei  –  blue
• Background  –  colourless

Notes

1. Amyloid displays apple green birefringence when viewed with crossed polarisers, one above and one below the section.
2. Sirius red F3B may also be used in this method (personal observation).

 

Reference
Highman, B., (1946),
Improved methods for demonstrating amyloid in paraffin sections,
Archives of Pathology, v 41, page 559

Bancroft, J. D. and Stevens, A.
Theory and practice of histological techniques,
Churchill Livingstone, London, England