[Histonet] Congo Red

Bob Richmond rsrichmond at gmail.com
Fri Mar 23 18:44:08 CDT 2018

Clemson Tiger Fran Pearsall asks:

>>Can anyone tell me what kind (or size) glass filter to use to perform
Puchtler's Congo Red? And are the filters re-useable?<<

I suppose you refer to polarization, necessary to examine a Congo red stain
for amyloid.

Your microscope needs a polarizer, preferably a full wave plate (first
order plate) system. Many pathologists don't have these on their
microscopes. Your urine lab across the hall has one, though you'll probably
have to spend five minutes cleaning and aligning the microscope. You should
know how to evaluate your positive control, particularly if your
pathologist doesn't know how.

The most common positive control available in a surgical pathology lab is a
medullary carcinoma of the thyroid. Most (but not all) of these contain
some amyloid.

I've asked this question many times over the years and never received a
glimmer of an answer: amyloid is rather easily produced experimentally in
mice. Is this material commercially available, and is it permitted for use
as an amyloid control?

Bob Richmond
Samurai Pathologist
Maryville TN

More information about the Histonet mailing list