Phil, John,

I tend to agree with John on this one.
Anecdotes aside, see our friend Freida Carson on this topic.
"Formalin fixation for Electron Microscopy: A re-evaluation."
Carson, F.L., Martin, J.H., Lynn, J.A.  Am J Clin Pathol 59:365,1973.

Best regards,

Bryan

> ----------
> From: 	J. A. Kiernan[SMTP:jkiernan@julian.uwo.ca]
> Sent: 	February 17, 2000 12:47 AM
> To: 	Philip Oshel
> Cc: 	histoNet@pathology.swmed.edu
> Subject: 	Re: Formaldehyde. Does methanol really matter?
> 
> On Wed, 16 Feb 2000, Philip Oshel wrote:
> 
> > Well, yes, but this ignores the MeOH in formaldehyde, and it's because
> of
> > the MeOH that us electron types use paraformaldehyde. (There, I
> condemned
> > myself. I do do LM also, honest!)
> > 
> > And I made the mistake of trying to fix cultured macrophages with 10%
> NBF.
> > Distorted them horribly, because of the methanol.
> 
>   Does the methanol really make all that difference? Conc. formalin
>   contains about 10%, so there's only 1% in NBF. Back in 1968 or so,
>   I remember seeing some pretty good EM pictures of human thyroid
>   that had been surgically removed and had sat in NBF for some time.
>   It was then osmicated etc. The work was done by my PhD supervisor, 
>   the late Brian A. Young, in Birmingham (UK) and a student called
>   David Kill, who went on to become a dentist. I'm pretty sure they
>   published it - almost certainly in J. Anat. They also examined
>   bits of thyroid fixed in glutaraldehyde and in Karnovsky-type 
>   mixtures, which were better, but not impressively so.
> 
>   *** Has anyone done a severe comparison of 4% formaldehyde made from
>   formalin vs paraformaldehyde, for EM or LM?  There are lots of
>   anecdotes; mine is that I can't tell the difference for several
>   LM applications. Others will surely disagree, but is this because
>   of having made a controlled comparison?
> 
>   1% methanol might well be toxic to living (cultured) cells, but
>   that's hardly a fault in a fixative. 1% ethanol would be below
>   physiological levels; beer is 4% to 5%. 
> 
>  John A. Kiernan,
>  Department of Anatomy & Cell Biology,
>  The University of Western Ontario,
>  LONDON,  Canada  N6A 5C1
> 
>  
> 
>