AW: [Histonet] overfixation with formalin

[joelle weaver]

You're fine in my opinion- according to Fox. If you read the first paragraph as introduction, and then skip over to the section starting with "pentration paradox" to paragraph(s) 2-3 of page 846, I think your thoughts are addressed. I can send the pdf to anyone if they want to look it over. 




Joelle Weaver MAOM, HTL (ASCP) QIHC
 > From: gu.lang <@t> gmx.at
> To: Barry.R.Rittman <@t> uth.tmc.edu
> Date: Sun, 4 Nov 2012 09:13:00 +0100
> Subject: AW: [Histonet] overfixation with formalin
> CC: Histonet <@t> lists.utsouthwestern.edu
> 
> Thanks for your support.
> Another theory about margin effect could be, that the methylenglycol in
> formalin is the main reagens. Isn't it possible, that it acts like other
> alcohols with dehydration at the surface (0,2-0,4 mm). But I think this
> effect is too weak to inhibit the center to be fixed properly. I still
> think, that it is too short fixation (no time for crosslinking) that causes
> "bad" centers.
> Gudrun
> 
> -----Ursprüngliche Nachricht-----
> Von: histonet-bounces <@t> lists.utsouthwestern.edu
> [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] Im Auftrag von Rittman,
> Barry R
> Gesendet: Samstag, 03. November 2012 20:32
> An: histonet <@t> lists.utsouthwestern.edu
> Betreff: RE: [Histonet] overfixation with formalin
> 
> Gudrun
> I  would thank him for his opinion and move on.
> There has always been the unfortunate tendency to accept anything that is
> published or presented formally as if it were gospel.
> I am a lot more skeptical, give me proof.
> Barry
> ________________________________________
> From: histonet-bounces <@t> lists.utsouthwestern.edu
> [histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Gudrun Lang
> [gu.lang <@t> gmx.at]
> Sent: Saturday, November 03, 2012 1:41 PM
> To: histonet <@t> lists.utsouthwestern.edu
> Subject: [Histonet] overfixation with formalin
> 
> 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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