Re: [Histonet] paraffin vs. frozen

From:"Katri Tuomala"

from clinical laboratory point of view, most of the time we don't have a 
choice. Most of our work is done retrospectively on formalin fixed paraffin 
embedded material (FFPE). This is why many manufacturers produce antibodies 
meant for this purpose. In selection of the antibodies, the type of material 
you have to work with has to be kept in mind.
But the fact is, that not all antigens can survive or they are masked by the 
FFPE process. The masking has been largely overcome by many types of 
retrieval procedures : enzymatic digestion and use of heat in different 
buffers. But the antigens, which don't survive FFPE, must be demonstrated in 
frozen sections, fixed in various fixatives (or not fixed at all)depending 
on the antigen to be demonstrated. Usually these procedures are much faster, 
but morphology often suffers.
In a clinical lab, a procedure has to be in place for collecting specimens 
for frozen section work. For instance a technologist has to attend, when 
renal or muscle biopsies are performed by a clinician and proper and prompt 
handling of the specimen is essential.
I hope this is of some help to you. I'm sure other histonet members will 
come forward for more information.


Katri Tuomala
Hamilton, Ontario, Canada

----- Original Message ----- 
From: "Kalleberg, Kristopher" 
Sent: Tuesday, March 06, 2007 1:22 PM
Subject: [Histonet] paraffin vs. frozen

If anyone could give some insight as to what the differences are between
frozen sections and paraffin sections when performing IHC I would
greatly appreciate it.  I am running a study and the results for a few
of the markers I am not to happy with and am contemplating changing over
to frozen sections for upcoming studies.  Is there any rhyme or reason
as to why antibodies work better with frozens sections or paraffin
sections?  Any help will of course be greatly appreciated.

Kris Kalleberg
Research Scientist
Unilever R&D
40 Merritt Blvd.
Trumbull, CT 06611
(203) 381-5765
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