Re: Fixative Osmolarity/Osmoality

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From:Karen S Pawlowski <> (by way of histonet)
Date:Mon, 31 Jan 2000 22:47:20 -0500
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It could be your glycol methacrylate procedure.  I work on ears in JB-4
and I infiltrate the tissue over a full week, starting with 1 change in
50% ethanol, then 4 changes each in 70%, 95%, and 100% over 3 days or
more, then 3 changes in JB-4 without catalyst, with 2 of the 3 changes
going overnight. I used to do it faster and the tissue definitely looked
worse - the major components looked fine, but the fine structure of the
tissue, including nerve endings and other small delicate cells looked

Since you said the paraffins look fine, I don't think it's your fix.

Hope this helps,
Karen Pawlowski

On Thu, 28 Oct 1999, Joyce Christopher wrote:

> Our laboratory has become interested in how to adjust the
> osmolarity/osmoality of fixatives.  We conduct neurotoxicity studies
> with rodents.  The animals are currently perfused with the 10% buffered
> formalin after a flush with sodium nitrite.  We have recently identified
> vacuoles in the peripheral nerves (sciatic, tibial, sural and spinal
> nerve roots) which are embedded in glycol methacrylate.  We do not see
> this artifact in the tissues embedded in paraffin.  Some of our
> pathologists believe this is due to the high osmalitity found in our
> purchased fixative.  We understand that the recommended range is 400-600
> mOsm.
> Does anyone have experience with adjusting the osmoality of fixatives?
> Are there references that may help us to better understand this and how
> to make the adjustments?  Is this artifact possibly caused by something
> else?  If you can provide some answer to these questions please contact
> me.
> Joyce Christopher
> Bayer Corporation
> 913-433-5244

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