Re: F13 fixative - another formalin substitute

From:"J. A. Kiernan" <> (by way of Histonet)

Thank you Bob for drawing our attention to this recent paper
with its attractive title but disappointing content, and
conclusions that certainly cannot be applied to tissues other
than the two that were used as test objects, if even to those.

When the J Histotechnol arrived this morning, I immediately
read this paper, because comparative studies of 15-20
different fixative mixtures are not often seen.
I hope you are wrong in guessing that this paper will spawn
one or more proprietary brews.

It is clear that plenty of work was done in comparing many
fixative mixtures, but the criteria for "good" structural
preservation of nuclei, cytoplasm and microanatomical
features are not stated or illustrated. The same amount of
work could have generated a really useful comparison, if only
the authors had defined the questions that needed answering
and used appropriate test tissues. Placenta is a
ridiculous tissue for evaluating a fixative. Comparisons
require small pieces of organs with well defined structural
organization that is easily disrupted by or after inadequate

Freshly removed testis and kidney have traditionally been
used for this purpose, and so has the central nervous system.
In all these organs unnatural spaces develop around tubules,
glomeruli, cells etc if micro-anatomical fixation is poor.
These organs also contain several cell-types with distinctive
nuclear and cytoplasmic structure that is greatly influenced
by the type of fixation at a cytological level, and
their responses to several widely differing fixatives
have been well documented for many years.

It is well known that the effects of different fixatives
vary from one tissue to another, in their primary effects
and in the protection they confer against changes caused
by paraffin processing, handling of frozen sections etc.
Even if "F13" is better than formalin for placenta and a
type of ovarian tumour (and even this claim is not valid
on the strength of the evidence in the published paper),
there is no reason to believe the same mixture would be
useful for other specimens.

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1

On Wed, 13 Dec 2000 wrote:

> Date: Wed, 13 Dec 2000 17:39:42 -0500 (EST)
> From:
> To:
> Subject: F13 fixative - another formalin substitute
> The December Journal of Histotechnology just arrived, with yet another
> formalin substitute, which the authors call F13. The formula is rather
> difficult to extract from the article (I went through the article three
> before finally finding which PEG - in a table). Only two types of tissue
> evaluated, placenta and ovarian mucinous borderline tumor, neither a very
> difficult tissue to fix. One wonders particularly whether this fixative will
> work on skin.
> I suspect that this article will spawn some proprietary fixatives, and I'd
> suggest printing this note out for your formalin file!
> "Evaluation of ethanol-based fixatives as a substitute for formalin in
> diagnostic clinical laboratories"
> The Journal of Histotechnology Dec. 2000:23(4);299-308
> Adrian R. Warmington
> Department of Anatomical Pathology
> Royal Women's Hospital
> Carlton, Victoria 3053 Australia
> Jenny M. Wilkinson
> School of Biomedical Sciences
> Charles Sturt University
> Wagga Wagga, Australia
> Clyde B. Riley
> (same address as Warmington)
> F13 fixative consists of:
> 60% ethanol
> 20% methanol
> 7% polyethylene glycol (PEG 300) 7%
> 13% distilled water
> Tissues were left in the fixative for 24 hours, then processed through
> ascending alcohols, xylene, and 60C Paraplast (few more details).
> The only tissues tested were 4 placentas and 4 borderline mucinous ovarian
> tumors.
> Slides were seen by pathologists. Large numbers of immune stains were done.
> The photomicrographs in the article are difficult to assess for quality.

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