Hi

3.3. Congo Red staining

Prepare a saturated Congo Red solution by adding 2.5 g of Congo Red to a total volume of 250 ml of 50% ethyl alcohol. Undissolved material should be filtered through a Whatman #1 or equivalent filter paper (see Note 17). It is preferable to perform this staining on sections that have been mounted onto slides (see Note 18).

After defatting the tissue in xylene or CitriSolv®, it is hydrated by taking it through a series of ethyl alcohol solutions (100%, 95%, 80% and 70%, 1–2 minutes in each) before staining in the Congo Red solution for 1 hour.

The slides are subsequently dipped into a saturated lithium carbonate solution for 10–20 seconds and then rinsed for a similar period in tap water or distilled water (see Note 19).

Dip the slides for 5–60 seconds in 70% ethanol to get rid of some of the background staining, and then transfer the slides quickly through 80%, 95%, and two sets of 100% ethanol (15 seconds to 2 minutes in each) before placing them in xylene or CitriSolv for 5–10 minutes (see Note 20).

The slides can now be coverslipped with mounting media such as DePex (see Note 21).

Congo Red staining can then be viewed under plane-polarized light. Amyloid plaques should give apple-green birefringence, usually as a Maltese cross, whereas the neurons that are non-specifically stained will not emit birefringence (see Note 22, and Fig. 1). For an alternative Congo Red staining procedure, please refer to Chapter 24.

Its from this publication:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3859432/

Hi

Thank you Natasha for your kind support and suggestion. 

With regards,

Choudhury A.