Re: [Histonet] EZ-Fix

From:John Kiernan

If this mixture is the 2nd or 3rd item on a tissue
processor, what is the first? One of the functions
of a fixative is to protect the tissue against adverse
effects of processing. The fixative should be the first
liquid a specimen encounters. 

Why would anyone want to use an alcoholic formaldehyde
solution of unknown composition? There are plenty of
published mixtures, mostly made with alcohol, formalin
and acetic acid. All these liquids are inexpensive and
are present in every lab that does histological work. 

There are also excellent published alcoholic fixatives 
that do not contain formaldehyde: Clarke's (3:1
has been around for 154 years. Carnoy's (alcohol:
chloroform:acetic, 60:30:10 ml) is about 115 years old.
Methacarn (with MeOH instead of EtOH) is supposed to 
be better; I haven't used it myself, but am inclined
to believe Holde Puchtler, who introduced methacarn.
"Modified Carnoy" (James & Tas, 1984) is Carnoy with
only 5 ml of acetic acid; it doesn't remove stainable
RNA, which can happen with unduly long (overnight)
exposure to regular Carnoy's. 

These alcohol-acetic fixatives can all give better 
micro-anatomical structural preservation better than is 
seen after neutral formaldehyde. Their reactions with 
proteins and nucleic acids are almost instantaneous, so 
fixation occurs with penetration - a few hours for 
ordinary specimens. These fixatives also do most of the 
dehydrating, and the specimens can be taken straight into 
the first 100% alcohol, saving time and materials.
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
Paula Lucas wrote:
> Hello,
> Has anyone heard of or tried a product called EZ-Fix?  A vendor told my
> administer of this, so I need to do some research on the product.
> It's described as a DMSO activated buffered alcoholic formalin that is used
> in the second and third station of the tissue processor.  It is recommended
> for breast of other fatty tissues.  It supposedly is 8x faster than formalin
> and 5x faster than Pen-Fix from Richard-Allan.

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