[Histonet] Re: Congo red

[Bob Richmond]

Some more points about trouble-shooting a weak Congo red stain:

Sections are commonly cut at 8 to 10 µm, as several people have noted.

I think that amyloid deteriorates on slides stored when they're cut
but not deparaffinized - in something like a month.

Your control may simply stain weakly, however you stain it. Good
amyloid controls are hard to get. What tissue does your control slide
come from? Lately most of the ones I've seen are taken from human
amyloid-containing medullary thyroid carcinomas.

Are your pathologists using polarization to look at the slides?
Amyloid stains require a high quality polarizer, which pathologists
often aren't allowed to have.

Finally, I've asked these two questions on Histonet several times, and
never had a response:

1. Amyloid is fairly easily produced in experimental animals such as
mice. Is this material ever used as an amyloid control?

2. Has anybody tried Anatech's "Amyloid Red" stain?

Bob Richmond
Samurai Pathologist
Knoxville TN