[Histonet] Apple Green Birefringence in Amyliod slides

[Morken, Timothy]

Ken, Yes, polarized light and apple green birefringence is diagnostic for amyloid with congo red and is the best practice. If you have a problem with known control slides  there are two possibilities: 1) make up fresh solution. The pH has to be right. Or 2) try other control slides. Maybe you cut through the amyloid area. 

Because we have hundreds of microscopes in our department most just use polarized film as the polarizer (put over the light source) and another put over the top of the slide as the analyzer. Turn one of the polarizing slides and you will see the birefringence appear. 

Source: 
"Polarizing film, 2"" x 2"" , PK/10 (BEST For use as a microscope polarizer)"	Cat# S07372	Thermo Fisher Sci Health	$36.75	PK/10	"2" x 2"	

These are polarized film mounted in 2" film holders (like the old Kodachrome slides). 

Cheap and effective. (and avoids consternation from people losing expensive microscope polarizers)

Tim Morken
Supervisor, Electron Microscopy/Neuromuscular Special Studies
Department of Pathology
UC San Francisco Medical Center


-----Original Message-----
From: Ken M via Histonet <histonet at lists.utsouthwestern.edu> 
Sent: Tuesday, July 28, 2020 11:43 AM
To: histonet at lists.utsouthwestern.edu
Subject: [Histonet] Apple Green Birefringence in Amyliod slides

Hi everyone.  I was wondering if anyone out there has any experience with diagnosing Amyloid tissue using Congo Red stained Kidney using polarized lenses.  Is it common to use polarized light to detect Amyloid deposits?  Does the absence of the "apple green birefringence" indicate a problem with the control tissue or the control slides?  Should this green bifringence always appear to confirm the diagnosis?  I know that the tissue should be cut thicker than normal (we usually cut at 5), but in the future maybe we will cut at 7 or 8?
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