Jason Wiese notes:
Presto-fixe II Active ingredients:
1.0 Molar Formaldehyde
0.2 Molar Glyoxal
PVP [polyvinylpyrrolidone?] (macromolecular colloidal membrane
This is a totally irrational proprietary formula of the sort John
Kiernan used to rail against - where's John now that we need him? If it
works as a disclosing fixative or postfixative, it's because it
contains an alcohol and formaldehyde. Neutral buffering isn't desirable
with such fixatives, but who knows what pH it's buffered to? - The
glyoxal is an additional aldehyde fixative, and I can think of no
reason to mix them - you probably get the disadvantages of both. People
have put things like PVP and middle range Carbowaxes into fixatives for
a long time, but I'm not sure they do any good. - You have no way of
knowing how the fixative supports immunohistochemistry, and it would
take long and expensive trials to find out - and wouldn't be FDA
approved for breast cancer anyway.
Methyl salicylate (oil of wintergreen) and cedar oil were once
recommended as disclosing fixatives, but they aren't practical -
time-consuming, expensive, smelly, and sometimes toxic.
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