[Histonet] question of the day - embedding

Julie Trejo jtrejo2 <@t> slu.edu
Wed Feb 18 08:55:55 CST 2009

I've worked in several places and only one actually kept the tissues in hot
paraffin at the embedding station and usually had alot of complaints on the
brittleness of the tissues.  I agree that there is no need for "extra
cooking time" in melted paraffin, but I have learned a nice trick from a
colleague in a positive manner for fatty tissue.  Sometimes the fatty tissue
is still raw-ish in the middle but would like to not re-process it, just
fill the mold with melted paraffin and place it in the holding chamber on
the embedding center.  Exchange the paraffin every 20-30 minutes or so and
after an hour or so, it is no longer raw. It cuts ALOT better. It helps with
the fatty tissue, and also shows you the effect of having the tissues in the
melted paraffin too long.  Just a tip


On Wed, Feb 18, 2009 at 8:25 AM, Shelly Christenson <
Christen <@t> vet.k-state.edu> wrote:

> We also don't keep melted paraffin in the holding chamber of the embedding
> center. We keep the chamber just a little warmer than the melting point of
> the paraffin, been doing it this way for as long as I have been working here
> at the Veterinary diagnostic lab at KSU ( around 20 yrs). I also don't like
> the tissue to be left to long in hot paraffin and I still find that certain
> samples are still brittle, I know that processing schedule and size of
> sample has a lot to do with it, but we have only one processor and have to
> run all of our samples on the same program, so we soak the blocks a little
> longer on the ice.
> Shelly Christenson HT (ASCP)
> Veterinary Diagnostic Lab
> Kansas State University
> >>> Tracy Bergeron <tracy.bergeron <@t> biogenidec.com> 2/17/2009 3:14 PM >>>
>  Hi all question/dilemma of the day.
>        I have been of the view that the longer tissue sat in melted
> paraffin the harder it got, especially animal tissue.  So with that said,
> for the past nearly 10 years I have not used melted paraffin in the
> holding chamber of the embedding center.  I just keep the chamber warm,
> and work that way.  Thus keeping the tissue from continuing to cook and
> harden in the wax.
>        Everyone else I am currently working with has never seen the
> method I use, and firmly believe that this causes harm to the tissues if
> they are not in paraffin.
>        Thoughts ideas etc.  I am dying to know if I am the only one that
> worries about length of time that animal tissue sits in paraffin.
> Thanks.
> Sincerely,
> Tracy E. Bergeron, B.S., HT, HTL (ASCP)
> Associate Scientist III, Pathology
> Comparative Pathology Laboratory
> Biogen Idec
> 14 Cambridge Center
> Cambridge, MA 02142
> Direct:  617-914-1115
> Fax:  617-679-3208
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Julie Trejo, HT(ASCP)cm

Saint Louis University
Department of Dermatology

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