This is a bit long. It's another of my HistoNet replies
  that says, "You must know what you're using, because if
  you don't you might end up in the brown & sticky."

  What is Penfix?  If it's different from formaldehyde it
  will probably have different effects on the structure
  of cells and other parts of the tissue, and on the
  results obtained with different staining methods. It is
  important to know what you are working with, and how it
  works. Formaldehyde has many faults and is rarely used
  correctly (especially in busy pathology labs), but its
  actions are pretty well understood, and its shortcomings
  should be easily recognized by the person examining the
  stained slides. The same is true of the ingredients of
  other fixatives that have been around for many years.

  I'm not claiming that all older fixatives are good;
  many of them are much worse than formalin. My point is
  that it's essential to know what the fixative does to
  the tissue. No other part of the processing procedure
  has a greater effect on the fine structure or on staining
  properties with dyes, antibodies etc.

  Does the label on the Penfix bottle tell you what's in it,
  and how much of each ingredient? If it does, you're paying
  for someone else to mix it instead of making your own -
  nothing wrong with that if you've got the money. If the
  ingredients are a trade secret can you ever justify using
  it? No good journal would accept a paper when the results
  had been influenced by some mixture whose composition was
  unknown to the authors. And imagine the pathologist, being
   sued for a wrong diagnosis, explaining to the judge that
  "No, your honour, I don't know whether I'd have got it
   right after formalin or Bouin. We were trying this new
   stuff that the sales rep said was better ..."

  There is an intermediate condition, where a fixative mixture
  is semi-secret, with the active ingredients revealed and their
  mode(s) of action explained by the manufacturer, but without
  enough information about concentrations or minor components
  to allow a lab worker to make the stuff from scratch. Anatech's
  "Prefer" is an example of this type. The rationale and principal
  ingredient are adequately explained but the MSDS sheet makes it
  quite clear that the detailed composition is an undisclosed
  trade secret. Some "proprietary" zinc-formaldehyde mixtures may
  also come in this category but in this case there is no shortage
  of published mixtures, including one from 1895 that's only
  2 or 3 years younger than the first use of formaldehyde in
  microtechnique.

  Please not that this is not an attack on Penfix, which I hadn't
  heard of before the recent exchange of HistoNet emails. It may
  well be an excellent product, and if its manufacturers monitor
  this newsgroup they will surely send us an account of what
  their product is. I hope they'll also send something to a
  peer-reviewed journal. Proper publication could only help their
  cause and increase their sales.

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1
   Phone: (519) 661-2111
   FAX (Department): (519) 661-3936
   E-mail: kiernan@uwo.ca

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On Thu, 13 Jan 2000, WAYNE HOLLAND wrote:

> You will like Pen Fix alot. You do not have to Formalin fix first.
> But there is a limited time it should be in Pen Fix, I think 36 to 48
> hours, but check with the insert.
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