Congo red staining can be performed on frozen sections, obtained from
cryostat or microtome, without any troubles (see for instance
You can use thioflavin-S as an alternative to Congo red. If results are
still negative, it remains possible that amyloid-beta peptides are not
aggregated (therefore not stained by the previous dyes) but only present
in the tissue as diffuse deposits (you can do IHC with dedicated
antibodies to check this possibility).
> Message: 15
> Date: Thu, 26 Apr 2007 10:35:47 -0400
> From: "Monfils, Paul"
> Subject: [Histonet] congo red on frozen sections?
> Content-Type: text/plain; charset="iso-8859-1"
> I was asked to do a congo red for amyloid on a mouse brain that had been formalin fixed, sucrose infiltrated, and frozen. The researcher was certain that this brain would have a high level of amyloid. I used a positive control that was human tissue, formalin fixed, paraffin embedded. The control slide stained perfectly. The mouse brain shows absolutely nothing. Has anyone successfully done congo red staining on frozen sections? Do you see any other possible problems in what I described?
Laboratoire de Neurobiologie de l'Apprentissage,
de la Mémoire & de la Communication,
NAMC, CNRS UMR 8620, Bât 446
91405 Orsay Cedex, FRANCE
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