[Histonet] IHC on paraformaldehyde-fixed

[Tony Henwood]

Interesting point.
Since 10% buffered formalin (made from the concentrated 38%
formaldehyde) contain about 1% methanol, has it been shown that this has
a deleterious effect on ANY antigens or are we expecting this worse case
senario as being the norm?

I am not aware of any antigens (or antigen-antibody combination) that
has been badly effected by 10% formalin that is NOT effected by 10%
formaldehyde. Are you aware of any??

Regards

Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC)
Laboratory Manager & Senior Scientist
Tel: 612 9845 3306
Fax: 612 9845 3318
the children's hospital at westmead 
Cnr Hawkesbury Road and Hainsworth Street, Westmead 
Locked Bag 4001, Westmead NSW 2145, AUSTRALIA 




-----Original Message-----
From: anh2006 <@t> med.cornell.edu [mailto:anh2006 <@t> med.cornell.edu] 
Sent: Friday, 5 December 2008 1:31 AM
To: Tony Henwood; Jan Shivers; histonet
Subject: Re: [Histonet] IHC on paraformaldehyde-fixed


So true. However, be aware that 10% neutral buffered formalin we use has
methanol in it which may affect certain antigens so there may be some
difference in staining (hence why for mouse work we now only use 4% PFA
in pure PBS). It is good to be aware of the other ingredients in your
fixative solutions, whether commercially prepared or a homemaede recipe,
as it isn't only the formaldehyde fixative which can make a difference.


-----Original Message-----
From: Tony Henwood <AnthonyH <@t> chw.edu.au>

Date: Thu, 04 Dec 2008 09:35:09 
To: Jan Shivers<shive003 <@t> umn.edu>;
histonet<histonet <@t> lists.utsouthwestern.edu>
Subject: RE: [Histonet] IHC on paraformaldehyde-fixed


Gee I hate the term paraformaldehyde (as many of you probably know)

This is an example of how confusion of terms can cause unnecessary work.
Is "4% paraformaldehyde" different from 4 % formaldehyde?

No

Should any procedure done to tissues fixed in "4% paraformaldehyde" give
results different to those fixed in 4% formaldehyde or 10% formalin? 

No since they are the same thing.


As Manoonkitiwongsa and Schultz (Histochem J 34: 365-367, 2002) state
when paraformaldehyde actually becomes a fixative, it is no longer
paraformaldehyde by chemistry or fixation capacity. Rather, it is
formaldehyde in water without methanol or any other stabiliser. Without
heat and an alkaline environment, paraformaldehyde in water is simply a
paraformaldehyde suspension with little fixation capacity. If the
fixative is prepared from paraformaldehyde then it should be termed 4%
formaldehyde freshly prepared from paraformaldehyde. If a concentrated
formalin solution (40% formaldehyde) is used, then it should be termed
10% formalin.

If you do a search on Histonet for paraformaldehye, you will find that
this topic has been extensively discussed.

Regards

Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC) Laboratory
Manager & Senior Scientist
Tel: 612 9845 3306
Fax: 612 9845 3318
the children's hospital at westmead 
Cnr Hawkesbury Road and Hainsworth Street, Westmead 
Locked Bag 4001, Westmead NSW 2145, AUSTRALIA 




-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Jan
Shivers
Sent: Thursday, 4 December 2008 8:34 AM
To: histonet
Subject: [Histonet] IHC on paraformaldehyde-fixed


Has anyone ever done IHC on parafomaldehyde-fixed tissues, and if so,
how well did it work?  Will the same antigen-retrieval methods used with
formalin-fixed tissue be applicable?

I'm asking for an investigator, who already has his tissues fixed in
paraformaldehyde.

Jan Shivers
Senior Scientist
Pathology Teaching Program
Histology/IHC/EM Section Head
University of Minnesota
Veterinary Diagnostic Laboratory
1333 Gortner Ave.
St. Paul, MN  55108
612-624-7297
shive003 <@t> umn.edu_______________________________________________
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