Re: PTAH Staining, Zenker etc.
|From:||"J. A. Kiernan" <email@example.com>|
On Mon, 30 Oct 2000, Rae Ann Staskiewicz wrote:
> When we do the PTAH, we mordant in Zenker's which we buy from Newcomer
> Supply. It does not contain mercury, instead I believe it is zinc. The
> PTAH still works wonderfully.
Zenker's fixative is a chromium-mercury-acetic mixture that was
indroduced in 1894, at about the same time as formaldehyde (Blum,
1893) and formaldehyde with zinc chloride (Fish, 1895). At that
time chromium trioxide, potassium dichromate and mercuric chloride
had all been used in fixative mixtures for 30 or more years.
The first published substitution of zinc salts (chloride or
sulphate) for mercuric chloride in mixtures containing potassium
dichromate may be a short note by Barszcz,CA (1976): Use of zinc
chloride in Zenker-type fixatives. Histo-Logic 6(4), 87.
The point I'm trying to make is that if someone is selling a
non-mercury liquid as "Zenker's fluid" he can expect to be
haunted by Zenker's ghost, and may the fibres of his rectus
abdominis muscle lose their striations and become swollen,
amorphous and darkly staining (Zenker's degeneration).
Zinc salts and mercuric chloride do not react identically with
proteins. otably, zinc chloride or sulphate lowers the pH much
more than mercuric chloride (which is largely unionized in water).
Zinc salts probably do not provide the same sub-microscopic
texture of cytoplasmic coagulation as that brought about by
mercuric chloride, but this probably does not matter for most
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1
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