[Histonet] IHC edge effect

[Dimitri Scholz]

I would agree with Mesruh: there could be different reasons.
Own experience: if you stain large semithin Epon sections with toluidin
blue, edges are usually darker stained than the center. At least for this
case, we can exclude drying and be sure the different penetration of osmium
fixation is the reason.
In case of immunolabeling, however, my first move would be to check if the
sections are dried, which could cause non-specific binding or even some
specific one caused by antigen retrieval (each tissue damage could work as
an antigen retrieval!).   

Regards,
Dimitri

Dimitri Scholz, PhD, Dr. Sci.
Director of Biological Imaging
Assotiate Professor
Conway Institute 
University College Dublin (UCD)
Belfield, Dublin 4 
Ireland
Tel: +353-1 716 6736


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of mesruh
turkekul
Sent: 13 January 2010 17:57
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] IHC edge effect

Dear Colleagues,


In my opinion the edge effect problem has many different components. In each
particular case the reason/reasons for edge effect are different.
Sometimes I observe that the staining intensity gradually decreases towards
the center of the section. In this case I think this is mainly fixation
problem.
I had experienced edge effect with manual as well different automated IHC
staining systems. Sometimes adjacent sections from he same block give
different intensity of edge effect with different antibodies/protocols.
Sometimes the edge effect is due to the trauma caused during
cutting/crossing the specimen before fixation.
Sometimes due to HIER methods or drying of the sections during staining. And
different antibodies/IHC protocols have different sensitivities to all of
the above phenomena that tortures the tissue/section.
All the answers given before to that question are correct.


Regards,
Mesruh Turkekul
Memorial Sloan-Kettering Cancer Center
New York, NY 10021
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