Puchtler, Sweat and Levine's
Congo Red for Amyloid

Solutions

Mayer's hemalum

Fresh 1% sodium hydroxide in distilled water

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 salt	50	mL
1% sodium hydroxide	0.5	mL
Use within 15 minutes.

Working Congo Red
Stock congo red	50	mL
1% sodium hydroxide	0.5	g
Use within 15 minutes

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 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  –  colourless

Notes

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

 

Reference
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

Bancroft, J.D. and Stevens A. (1982)
Theory and practice of histological techniques Ed. 2
Churchill Livingstone, Edinburgh & London, UK.