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Highman’s Congo Red for Amyloid

Highman's Congo Red

for Amyloid



  • Mayer’s hemalum
  • Congo red
    Congo red0.5g
    Distilled water50mL
    Ethanol, 100%50mL
  • Alkaline ethanol
    Ethanol, 80%100mL
    Potassium hydroxide0.2g

Tissue Sample

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


  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  – colorless


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

Safety Note

Prior to handling any chemical, consult the Safety Data Sheet (SDS) for proper handling and safety precautions.


  1. Highman, B., (1946),
    Improved methods for demonstrating amyloid in paraffin sections,
    Archives of Pathology, v 41, page 559
  2. Bancroft, J. D. and Stevens, A.
    Theory and practice of histological techniques,
    Churchill Livingstone, London, England