[Histonet] RE: Paraffin-Plastic Stratification/Congo red problem

[Ingles Claire]

I believe amyloid does fade with age on cut slides. Frieda sited Bancroft and Cook that intensity decreases with age and "long-standing" deposits stain less intensely than smaller "Newly formed" deposits. She also lists a Crystal Violet method in the 3rd edition, but that it is more of a rapid screening technique and is not as specific as Congo Red. 
Claire

________________________________________
From: histonet-bounces <@t> lists.utsouthwestern.edu [histonet-bounces <@t> lists.utsouthwestern.edu] on behalf of Wheelock, Timothy R. [twheelock <@t> mclean.harvard.edu]
Sent: Friday, January 23, 2015 2:00 PM
To: 'histonet <@t> lists.utsouthwestern.edu'
Subject: [Histonet] Paraffin-Plastic Stratification/Congo red problem

Hi Jeffery:

Yes, I notice the same "paraffin dust bunnies", perhaps especially since I use a embedding paraffin that has a fair amount of plastic.
Before I embed my brain tissue, I mix the embedding media thoroughly, until the solution is clear.

As for your Congo Red problem, I wish that I could help you.
I am now experiencing the same problem, except that it affects the positive controls as well.
The staining is there, but much fainter than it should be.

I usually immerse albumin coated slides in 1% Congo red for 15 minutes, differentiate them with Potassium Hydroxide for 3 dips, counterstain with Harris Hematoxylin for 1 minute, differentiate with acid alcohol for 5-10 dips, immerse in running tap water for 10 minutes, immerse in 95% ethanol for 2 dips, then dehydrate and mount.

Tim




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