Re: Formalin

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From:Paul Millikin <> (by way of histonet)
To:histonet <>
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Marykay Olson wrote:
> To All:
>   One of the grad students accidentally put rabbit spleens in 37%
>Formaldehyde instead of 10% NBF. Are they ruined ? What happens to
them? Is it still possible

>          Mary Kay Olson
>          CBN and Anatomy
>           Loyola Univ. Medical Center
>           Chicago,Il.

All you can do is try.  Might try one overnight in 70% ethanol, but
any hope would still be pretty slim.

For future reference, spleens are VERY hard to fix WELL, anyhow.
They tend to be so full of RBC that they behave like a thrombus or
an embolus.

When simply thrown intact into an immersion fixative, the outer,
subcapsular 2-3 mm tends to fix, but the rest is usually rotten.
Instead of brown and firm like the subcapsular area, it tends to be
soft, red, and mushy.  That's one reason we don't know any more about
splenic histology than we do.  We've been looking at rotten,
autolyzed tissue for too long.

Slicing (breadloafing) the specimen every 2-3 mm before immersion
causes considerable improvement, and should be a must for everyone
interested in spleens.

Some people prefer perfusion fixation, which is tedious, requires a
certain amount of talent (AND luck!), and washes a considerable
amount of blood out of the sinuses.  By washing cells out of the
sinuses, such rinsing obviously produces a new kind of artefact, and
some people object to that.  However, overall fixation is uaually
considerably better, so it's all a trade-off, depending on what
you're looking for.

Breadloafing before immersion is a minimum in our department,
research specimen or surgical specimen.  For the latter, we try to
get the sp
ecimen in less than 5 minutes after its removal from the patient
because we don't KNOW what we're looking for.

Paul Millikin
Peoria, IL

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