[Histonet] Formalin Fixation times for IHC samples

[Hawkins, Hal K.]

One factor that has not been mentioned yet with regard to this
discussion of fixation time is the effect of agitation.
Those of us who do autopsies know well that there is often poor
penetration of fixative between samples resting in a static container.
Agitation during fixation can reduce this problem and reduce the time
necessary for fixation by maintaining a nearly constant concentration of
fixative at the surface of each piece of tissue.

Hal Hawkins, UT Medical Branch, Galveston, TX

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of
mucram11 <@t> comcast.net
Sent: Thursday, February 24, 2005 9:05 AM
To: Connolly, Brett M; 'ajennings <@t> unmc.edu';
Histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] Formalin Fixation times for IHC samples

I agree with Brett about the article however, a great deal of what we do
in histology is empirical or just accepted as the way things are always
done.  Over the past decade as IHC has become so important and time has
been shortened for many laboratories the arguments about fixation are
increasing.  The time tissue is in fixative should include the not only
processor time but the time from grossing through processor fixation.

If the sample comes and is grossed early (mid morning) and placed in a
holding container of fixative it may have different for better or worse
staining than later arriving specimens. The tissue that comes in at 2PM
and gets grossed in at 3PM and placed in the holding container for 30
minutes to an hour and then on the processor will often appear very
different or "under fixed" in comparison.  We don't  look at those
differences in time of fixation as often as we should and we are not
always allowed to make up the time required in fixative.  If the
specimen goes in late enough the fixation may be completed more by
alcohols during dehydration than 10% NBF and this can effect staining as
well.

Pam Marcum

-------------- Original message -------------- 

> Take a look at the J. Histotechnology 24:3, Sept 2001....special issue
on 
> Fixation. It includes a couple of articles dealing with fixation and
IHC. 
> 
> Brett 
> 
> Brett M. Connolly, Ph.D. 
> Merck & Co., Inc. 
> MRL, Imaging Research 
> WP26A-3000 
> PO Box 4 
> West Point, PA 19486 
> PH 215-652-2501 
> fax. 215-652-2075 
> e-mail. brett_connolly <@t> merck.com 
> 
> 
> -----Original Message----- 
> From: histonet-bounces <@t> lists.utsouthwestern.edu 
> [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of 
> ajennings <@t> unmc.edu 
> Sent: Thursday, February 24, 2005 9:06 AM 
> To: Histonet <@t> lists.utsouthwestern.edu 
> Subject: RE: [Histonet] Formalin Fixation times for IHC samples 
> 
> 
> 
> 
> 
> 
> Great timing on this topic 
> 
> I have been looking for a review article that actually puts in print
the 
> data collected on over fixation or under fixation in samples that will
be 
> used for IHC. To include the eventual breakdown of formalin and need
for 
> 10-20 times volume for proper fixation. Is there such a paper with all
of 
> information that histologist reverberate and others ignore? 
> 
> 
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