RE: Paraffin processing using agar

From:"McCormick, James"

Good idea but denatured agar (after formalin and alcohol) will not dissolve.
Tough problem without destroying the tissue. I will be interested if someone
has a solution. J.B.McCormick M.D.

-----Original Message-----
From: J. A. Kiernan []
Sent: Tuesday, April 23, 2002 10:55 PM
To: Sue Reilly
Subject: Re: Paraffin processing using agar

Sue Reilly wrote:
> We regularly use agar to oreintate tiny specimens that cannot be seen
> properly when embedding in paraffin.
> I have found this a very sucessful technique ...
> Suddenly, I have a batch where the agar has shrivelled up and is extremely
> brittle and will not cut. ...  looking for a way to rescue these valuable 
> samples. I would be very greatful of any suggestions.

You didn't say, but is it correct to assume the shrinking
and hardening occurred during dehydration, clearing or
infiltration? (It should be possible to find out by processing
some blobs of the same agar solution and prodding at every

I've never had to do this, but the obvious salvage procedure
would be to melt the block and take the hard agar pellet back 
through all the solvents to water, heat it up until the agar
melts, and start again - with a new batch of agar solution.

John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1

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