[Histonet] Davidson's fixative and IHC question

[Tyrone Genade]

Hello,

I am using Davidson's fixative to fix whole fish and I am very happy with
the results. I had tried 4% PFA but had issues with collapsed eyes and
detached retinas... No such issues with Davidson's or Bouin's. In my
experience I get sharper nuclear staining by H&E and better declacification
with Davidson's. The integrity of the brain tissues is good with less
shrinkage than with Bouin's.

I fix whole fish over night and then move them to 70% ethanol.

I had issues with autofluoresence with Davidson's (no surprise there) but
it was easily remedied using Gayle Callis' glycine protocol (available
somewhere on histonet). Same story for Bouin's.

Some antigens are lost and seem irretrievable.  The anti-GFAP antibody,
GA5*, worked fine on PFA fixed fish but the epitope couldn't be retrieved
in Bouin's fixed fish. I'm not sure about Davidson's but using heat induced
citric acid antigen retrieval (pH 5, 80 min at 60 oC) has worked for
several epitopes.

* If memory serves, this is a phosphate-epitope so that could be something
to look out for.

I would advise testing several different fixatives and seeing which works
the best for your application. If you are working with soft tissue, such as
brain, a zinc fixative might be better for the preservation of delicate
epitopes: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1919503/ .

Bye

Tyrone