[Histonet] AFA fixative

[Geoff McAuliffe]

Hi Christina.

    Well, AFA is alcohol + formaldehyde + acetic acid, none of these are 
good for you but neither is buffered formalin. That said, the alcohol in 
AFA will "carry" the other components across skin by acting as a solvent 
to the lipids in skin. Aqueous fixed like buffered formalin are much 
less likely to do this. So the good penetration properties of AFA could 
render it more toxic. Gloves would solve the problem.

Geoff

Cristina Nunes wrote:

>Dear histoneters,
>For several years, in the Institute where I am working, the main fixative
>used for the preservation of gonads of fish was AFA, with apparently good
>results. Then, at a given moment (before I arrived to the Institute), it was
>decided to change from AFA to a formalin solution because of the higher
>toxicity of the former. The histological results were slightly less good but
>for practical reasons (most fish tissue fixations occur at sea, on board the
>research vessels), it was considered to be the best solution. However,
>nobody was able to explain me why AFA is much more toxic than a formalin
>solution (I am sorry for my ignorance in terms of chemistry). Could anyone
>clarify me on that point?
>Many thanks in advance and a very nice week-end.
>Regards,
>Cristina Nunes.
> 
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>><<<>
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>Cristina De Amaral P. Nunes
>INIAP-IPIMAR Fisheries and Sea Research Institute
>Marine Resources Department
>Avenida Brasília
>1449-006 Lisboa
>Portugal
>Tel: + 351 21 302 71 55
>Fax: + 351 21 301 59 48
>Email: cnunes <@t> ipimar.pt
>  
>
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Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
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