RE: [Histonet] varying time in formalin

From:"patsy ruegg"

It depends on which marker you want to use, some are more masked by long
formalin fixation than others.  Most all can be retrieved with enough
pretreatment which may require enzyme digestion and HIER methods combined,
some are best retrieved with lower heat for longer periods of time, I have
done some hier in a waterbath set at 37dc overnight, or a wb at 72dc for 3
hrs., etc.  There is one marker (Ki67) that I was not able to demonstrate
after 1 yr in formalin, Chris van de Loos did some fixation studies and
found that ki67 was lost or not accessible after 3 mos in formalin, most all
others I have tried at least have been demonstratable even after 1 yr in
formalin.  Under fixation is more of a concern for me.

Patsy Ruegg, HT(ASCP)QIHC
12635 Montview Blvd. #216
Aurora, CO 80010
fax 720-859-4110 

-----Original Message-----
[] On Behalf Of Rene J Buesa
Sent: Saturday, February 24, 2007 7:10 AM
To: Stephens, Elizabeth Humes;
Subject: Re: [Histonet] varying time in formalin

  As you well know, croslinkage by formalin during fixation (as well as
xylene as an antemedium) has cause the development of the Heat Induced
Epitope Retrieval (HIER) and, although there is not such a thing as
"overfixation", many consider that the longer a tissue is in formalin, the
more IHC is "affected".
  What I would suggest you to do is to get a fresh specimen, fix it for just
6 hours, process it and use it as a positive control against the specimen
kept the longest in formalin.
  Then you will be able to see the difference, if any at all!
  Just a thoght!
René J.

"Stephens, Elizabeth Humes"  wrote:
  Hi everyone! I am wondering whether anyone has looked at how much length
of time in formalin affects the ability to do immunohistochemistry? For
instance, I want to do a pathology study on heart valves but have hearts
that have been in formalin 1 year, 2 years, 3 years and am afraid this will
my results. I would be interested in IHC staining of matrix markers
including various collagen types, elastin, fibrillin, proteoglycans,
glycoaminoglycans, smooth muscle alpha actin, lysyl oxidase, prolyl

Thank you!!
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