RE: [Histonet] NFB vs. Paraformaldehyde

From:"Barry R Rittman"

Actually not to detract from the references below but a lot of the work
in this area was carried out by Karlsson and Schultze in 1965. They were
working with different fixatives for studying the electron microscopy of
the brain and found that indeed the buffer made a significant difference
to the final image. They also compared immersion via perfusion fixation.

-----Original Message-----
[] On Behalf Of Morken,
Tim - Labvision
Sent: Tuesday, November 09, 2004 10:42 AM
To: '';
Subject: RE: [Histonet] NFB vs. Paraformaldehyde


Way back in 1973 (ref below) Frieda Carson showed that when comparing
quality of fixation between formaldehyde and paraformaldehyde, the
buffer is
the critical factor, not the source of the formalin.

Paraformaldehyde is the solid form of formaldehyde. Once dissolved in
there is no difference between formalin from formaldehyde gas dissolved
water (what most of us use) and formalin made from paraformaldehyde.
commercial formalin has methanol included to prevent polymerization of
formaldehyde, that does not affect the fixative properties. 

So, in short,  it would be much better to have the students pay
attention to
the buffers that are used than the source of the formalin. Of course,
the formalin will be much easier with concentrate than having to

In fact, a good class experiment would be to compare the two with the

Carson, FL, Lynn JA, Martin JN: Formalin fixation for electron
microscopy: A
re-evaluation. Am J Clin Pathol 59:365, 1973.

Carson FL, Lynn JA, Martin JN: Ultrastuctural effect of various buffers,
osmolality, and temperature on paraformaldehyde fixation of the formed
elements of blood and bone marrow.  Texas Rep Miol Med 30: 125, 1972

Tim Morken
Lab Vision - Neomarkers

Free webhosting for US State Histotechnology Societies:

-----Original Message-----

Sent: Tuesday, November 09, 2004 6:51 AM
Subject: [Histonet] NFB vs. Paraformaldehyde

Good Morning Histonetters,

I would like to get an idea from those histotechs that work with mouse
tissue if they prefer NFB or Paraformaldehyde as a fixative for routine

I work for a group of 6 researchers, most of who do mouse work.   Their
do the necropsies, remove and block the tissue, make up their own
paraformaldehyde, fix and submit the cassettes to me from processing and

I would like everyone to change to NFB to standarize the fixation.  I
guarentee that no one makes Paraformaldehyde the same.  Some make it the
same day, some the day before, 2-3 days before  etc.

I am meeting with the big bosses this afternoon and would like some
ammunition if possible.

Thanks for the assistance.


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