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Puchtler, Sweat and Levine’s Congo Red for Amyloid

Puchtler, Sweat and Levine's Congo Red

for Amyloid



  • Mayer’s hemalum
  • Stock alcoholic salt
    • Saturate 80% ethanol with sodium chloride.
  • Stock congo red
    • Saturate 80% ethanol with congo red and sodium chloride.
    • Let stand for 24 hours.
  • Working alkaline alcohol
    Stock alcoholic salt50mL
    1% sodium hydroxide0.5mL

    Use within 15 minutes.

  • Working congo red
    Stock congo red50mL
    1% sodium hydroxide0.5mL

    Use within 15 minutes.

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. Stain nuclei with hemalum.
  3. Rinse well with distilled water.
  4. Place in working alkaline alcohol for 20 minutes.
  5. Place in working congo red for 20 minutes.
  6. Dehydrate rapidly with absolute ethanol.
  7. Clear with xylene and mount with a resinous medium.

Expected Results

  • Amyloid  –  Deep pink to red
  • Nuclei  –  blue
  • Background  –  colorless


  • Amyloid displays apple green birefringence when viewed with crossed polarizers, one above and one below the section.
  • This method is considered to be the most reliable of all congo red methods for amyloid.

Safety Note

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


  1. Puchtler, H., Sweat, F. and Levine, M., (1962),
    On the binding of congo red by amyloid,
    Journal of Histochemistry and Cytochemistry, v 10, page 355
  2. Bancroft, J.D. and Stevens A. (1982)
    Theory and practice of histological techniques Ed. 2
    Churchill Livingstone, Edinburgh & London, UK.