[Histonet] Reprocessing Protocol

[John Kiernan]

It makes no sense to heat a paraffin-infiltrated specimen in saline. Sodium chloride isn't soluble in hot paraffin or in any of the organic solvents used in tissue processing.

Heating in water may melt and float out all the wax and rehydrate a specimen, but does it matter if some wax remains?

Reprocessing is an attempt to correct the effects of incomplete dehydration. This can be done by taking the specimen back into the clearing agent (xylene or similar) and then into 2 changes of 100% alcohol (methyl, ethyl or isopropyl). Why rehydrate?

For a rehydrated specimen, why go "from formalin, using a schedule that would have been of appropriate length as used initially"?  This will surely produce, again,  a block that is incompletely dehydrated.

John Kiernan
London, Canada
= = =
________________________________
From: Etheridge, Sandra AFF:EX via Histonet <histonet at lists.utsouthwestern.edu>
Sent: October 12, 2021 5:19 PM
To: histonet at lists.utsouthwestern.edu <histonet at lists.utsouthwestern.edu>
Subject: Re: [Histonet] Reprocessing Protocol

Hi Curt,

We have used Taggart's Method quite successfully in the past for poorly processed tissues.  You can find it online.  The isotonic saline may help to rehydrate your tissues.

1.  Melt down the tissue block in the embedding centre block tray area and gently blot off the excess wax. Place the tissue in a newly labelled cassette.
2.  Place the cassette into a beaker of isotonic saline (0.9% sodium chloride) and place it in the 65 C incubator/oven for one hour. This will melt the residual wax which will rise to the surface of the saline.
3.  Remove the cassette from the saline, drain briefly and place in your processor from formalin, using a schedule that would have been of appropriate length as used initially.
4.  Embed and section as per usual.

Good luck!

Sandra Etheridge

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Subject: Histonet Digest, Vol 215, Issue 8

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Today's Topics:

   1. reprocessing tissue (Curt Tague)


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Message: 1
Date: Tue, 12 Oct 2021 15:14:54 +0000
From: Curt Tague <c.tague at pathologyarts.com>
To: "histonet at lists.utsouthwestern.edu"
        <histonet at lists.utsouthwestern.edu>
Subject: [Histonet] reprocessing tissue
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        <SJ0PR14MB43152C53B72BE198D958A018F1B69 at SJ0PR14MB4315.namprd14.prod.outlook.com>

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I have a problem... some tissue got processed very poorly, there was water in the system somewhere and a few blocks just look burnt.. the nuclei are faint and cloudy, no detail at all. I've tried the process of rehydrating with the 30% formaldehyde, glycerol and sodium acetate solution but they still process poorly, come out very brittle and just don't look good under the scope.

Does anyone have a magic bullet to salvage these specimens? I can send a pic directly if it helps.

Thanks,
Curt



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