[Histonet] (para)formaldehyde

[Geoff McAuliffe]

Greetings Mikael:

    What differences are you talking about? What leads you to suspect 
that one fixative is different from the other? And are all of the other 
variables controlled? Fixation time, temperature, method of application 
of the fixative, size of the tissue, etc.The amount of methanol in a 
"10% formalin" solution is 1.2-1.5% versus zero for  fix made from 
paraformaldehyde.

Geoff

Mikael Niku wrote:
> This has probably been discussed 1000s of times, but....
>
> I'm wondering to what extent dissolved paraformaldehyde really is equivalent
> to 4% formaldehyde or 10% formalin.
> In my experience, samples fixed in formalin and "4% PFA" as we tend to say
> are different when one does immunostaining or especially in situ
> hybridization. Formalin is of course traditionally used in pathology,
> whereas many labs doing immunos or ISH use "PFA".
>
> But what really causes the differences? Is it incomplete de-polymerization
> of paraformaldehyde, or perhaps the methanol typically included in formalin?
>
> -----------------------------------------------------
>  Mikael Niku, PhD, university lecturer            
>  University of Helsinki, Division of Nutrition
>  URL: mikael.nikunnakki.info
>
>  - What do I think of western civilization?
>    I think it would be a good idea!                       
>                                             Gandhi
> -----------------------------------------------------
> -----Original Message-----
> From: histonet-bounces <@t> lists.utsouthwestern.edu
> [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Tony Henwood
> Sent: 20. elokuuta 2008 4:42
> To: Lee Crosby; histonet <@t> lists.utsouthwestern.edu
> Subject: RE: [Histonet] in situ question
>
> Which the becomes 4% formaldehyde or equivalent to 10% formalin. Not 4%
> paraformaldehyde.
>
> 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 
>
>
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>
>   


-- 
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Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
675 Hoes Lane, Piscataway, NJ 08854
voice: (732)-235-4583 
mcauliff <@t> umdnj.edu
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