"Yandl, Emily" wrote:

> Hi all!
>
> We have a researcher here who is submitting normal whole mouse organs
> (liver, heart, lung, kidney) for paraffin processing for use as IHC
> controls.  Currently, she is fixing these organs in 10%NBF for 4 hours to
> retain as much immunogenicity as possible, however, I am worried that the
> organs are not completely fixing and are drying out in the alcohols.

    I would think that, unless the animal is being perfused,  4 hours is not
adequate time for fixation. Even with perfusion fixation, 4 hours is probably
more of a "stabilization" rather than fixation. Formalin fixes tissue slowly,
no way around it. Forty-eight hours is the "standard" for complete fixation.
    Fix longer and use antigen retrieval (if necessary) or maybe a
formalin-alcohol-acetic acid fix?

> What fixation procedures do those of you who work with mouse tissue use?
> How long in fix when doing IHC?  Are the organs grossed open prior to
> fixation or left whole?

    If you are fixing by immersion, even something as small as a mouse kidney
should be cut in half. I fix mouse brain by perfusion, then cut it up and fix
for 4 hours but that is for frozens, not wax sections.

Geoff
--
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Geoff McAuliffe, Ph.D.
Neuroscience and Cell Biology
Robert Wood Johnson Medical School
675 Hoes Lane, Piscataway, NJ 08854
voice: (732)-235-4583; fax: -4029
mcauliff@umdnj.edu
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