I agree with Rene, Barry, etc.
Geoff
On 11/3/2012 2:41 PM, Gudrun Lang wrote:
Hi histonetters!
I'm just attending a histo-course, where the teacher told us his opinion
about overfixation.
For him overfixation takes place in any formaldehyde solution with a
concentration above 5%. This should cause the margin-artefact, that leads to
false-positive IHC at the margins of the tissue and to false-negative
results in the center. The higher concetrated fixative should harden and
shrink the surface, so it cant be penetrated any more by the fixative.
I told him about the publication of Cecil Fox, who saw shrinkage only in
solutions with formaldehyde concentration above 30% (I think) and said, that
the methanol-part is responsible for that.
I believe, that these margin-artefacts are due to drying at the time of
biopsy or an effect of the needle-shot itself. (But believing is no
evidence)
In our lab we use 8% formaldehyde as standard fixative, buffered with
low-molar phosphatebuffer. There are no complains from the doctors about
margins.
Please help me with the histonet-wisdom. What's your opinion?
Bye
Gudrun Lang
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Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
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voice: (732)-235-4583; fax: -4029
mcaul...@umdnj.edu
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