[Histonet] Silly Question?

Rene J Buesa rjbuesa <@t> yahoo.com
Thu Dec 11 12:06:51 CST 2008

The "advantage" of para-formaldehyde is that you can prepare more easily any type of formaldehyde solution, at any concentration and also it does not have any additives (methanol) as "pure" formalin (37-50%formaldehydede) does.
In reality the fixation mechanism is the same and sometimes the whole issue boils down to personal preferences.
René J.

--- On Thu, 12/11/08, Pat Flannery <pjfnefro <@t> duke.edu> wrote:

From: Pat Flannery <pjfnefro <@t> duke.edu>
Subject: [Histonet] Silly Question?
To: histonet <@t> lists.utsouthwestern.edu
Date: Thursday, December 11, 2008, 11:58 AM

Please humor me on this if it's obvious (to everyone but me):  why do we use
paraformaldehyde (which is so inconvenient to make up) rather than buffered
formalin or just diluted formaldehyde itself?

It seems that around here, some folks prefer paraformaldehyde (either 2% or 4%)
and others use formalin, while some others stick to diluted formaldehyde (I see
all 4 on labels for specimens submitted for histology).  Is it mostly a matter
of personal preference or where you were trained (i.e. force of habit) or is
there a valid reason to use each solution (basically the same chemical once in
solution, merely buffered or not)?  The only answer I've gotten when
I've asked is, "That's what we always use."


-Pat Flannery (not a "real" histologist - I just play one in the lab)

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