RE: [Histonet] 4% PFA

From:"S Ladd"

I completely agree with you. I have done side by side experiments and found
the results to be far superior with 10% NBF or 10% formalin. For whatever
reason, the sections expand and distort more on the waterbath with 4%
formaldehyde made from paraformaldehyde (4%PFA) and are more difficult to
section. I think its the methanol (the very methanol everyone is trying to
avoid by using 4%PFA).


-----Original Message-----
[]On Behalf Of Joanne
Sent: Thursday, October 07, 2004 7:44 AM
Subject: Re: [Histonet] 4% PFA

4% PFA may be a good fixative in research setinng, but if the tissue is
routinely processed through alcohols to xylene, and embedded in paraffin,
the mouse brain tissue will be 'mushy' and impossible to cut well. If the
same tissue is re-fixed in 10% NBF and processed,the cut sections will be

>>> "Colleen Forster"  10/06/04 05:26PM >>>
4% PFA is a very good fixative. The difference between 4% and 10% is
that the PFA is made fresh each time and has no impurities added ex:
methanols. The formalin content in both comes out to about the same. It
is a standard fixative for many research labs. You can drop fix with PFA
or perfuse and then drop fix for additional time for very good fixation
and excellent results. I have used it for my mouse brain tissue for over
6 years with very nice results.

Colleen Forster
U of Mn

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