[Histonet] Re: Polyester wax (with earlier citations)


Hi John,

I don't think there are any reasons for using it now. When I used it in the
70's it was because one of our pathologists wanted to cut thin sections
from biopsies. The sections were good when you eventually produced any!! I
dabbled with Digol Distrearate for a while but found sectioning this
difficult too. Then along came methacrylate and the rest, as they say, is
history. The Pathologist in question was a John Southgate who had a lab in
his office for dabbling in histology procedures. He obviously got the
technical bug from his microbiologist father, of Southgate's Mucicarmine
fame. John Southgate also developed a Zenker-Susa fixative procedure for
biosy fixing which involved giving two pots, one for Zenker, and one for
Susa, to the nurse, who mixed both immediately prior to adding the biopsy.
There was then a max of 4 hrs fixation (if I recall correctly), followed by
a water wash to remove mercury. Processing was on a Technicon Ultra, with
it's oil heated bath. Embedding - this was before we had plastic cassettes
-was done using ice cube trays filled with hot wax from a small teapot
sitting on a stand heated with a bunsen burner. Specimen identification was
on small paper strip, the end of which was inserted into the cooling wax
block. A full tray was floated onto cold water and when the surface wax had
solidified, the whole tray was immersed. The times the labels would
separate from the wax block and time was often wasted  matching up
unlabelled blocks with paper labels. Then, a small guilotine was used to
coarsly trim away wax excess wax, before a flat blades spatular-type heated
iron was used to finely create the final block. The block was attached to a
wooden block which had it's surface heated by the heated iron. The specimen
label was attached to the wooden block and the heated iron was run over the
back of the wax block, with the hot wax allowed to drip onto the wooden
block and the wax block applied very quickly. It is not hard to imagine the
frustration of experienced microtomists when trimming in blocked caused
many to fall off indicating a trainee was learning this process and blocks
were not attached properly. And then the blocks had to be removed later
using a 'blunt' knife.

Ahhhh, they were the days, when many a day I'd go home with brown hands
after making up 10% formal saline, the smell of which was eased by the
gentle aroma of pipe tobacco wafting around the lab from the pathologist
who was performing a cut-up (grossing). I cannot remember hearing the word
safety then.

Well better get back to work.



                      John Kiernan                                                                                                     
                      >                        cc:      histonet-bounces@lists.utsouthwestern.edu                                      
                                               Stephen Eyres/GB-ALNWICK/RESEARCH/SANOFI@Research                                       
                      05/05/2004 06:23         rnishi@uci.edu                                                                          
                                               Subject: Polyester wax (with earlier citations)                                         

We tried Steedman's polyester wax in the early 1980s (Yes,
after reading the early 1950s literature!). Powder rather
than sections poured over the knife's edge. We gave up.

In the light of recent (1990s) advances, are there any
reasons for trying to master the lost art of sectioning
polyester wax? This embedding medium was introduced
shortly before the cryostat and long before antigen
retrieval. In one of Steedman's procedures polyester wax
was included in a one-step mixture with a Bouin-like
After 24 hrs the liquid was cooled, and when it had set
you could trim the block and (he said) produce ribbons
of sections.

Polyester wax reappeared in the 1970s, when it was widely
thought that immunohistochemistry worked best after little
or no fixation and avoidance of organic solvents, wax,
heat etc. This didn't catch on despite being published in
classy journals.

The comments from Stephen.Eyres@sanofi-synthelabo.com
(cited below) should help those who try to cut polyester
wax. Clearly it's a difficult medium to handle. Are there
any purposes for which it must be used?
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
Sarah Jones wrote:
> I tried polyester wax years ago and came to the conclusion I needed to
> be cutting in a walk-in-cooler.  I never thought of keeping the knife
> and block in the fridge, but it make sense.  I second the vote for any
> other method.  Unless you love challenges and have the patience of a
> saint.
> Sarah Jones HT(ASCP)
> Dept. of Vet. Anatomy & Public Health
> Histology Lab
> Texas A&M University
> College Station, TX 77843-4458
> phone: 979-845-3177
> fax:  979-458-3499

> >>>  5/4/2004 10:44:42 AM >>>
> Hi Rebecca,
> Many, many years ago I used 37 degree C MPT polyester wax. There are
> several major problems using the stuff. Key one is temperature. Blocks
> and
> knife were kept in the fridge, with both brought out just prior to use
> -we
> used a Cambridge rocker which meant transfer of knife to and from the
> fridge was easy. In the summer in our lab which had no air
> conditioning,
> there are minutes of cutting time available before the block and kife
> warms
> up and sectioning has to stop. One paper I read partly overcame this
> narrow
> curring window by using a flower sieve packed with dry ice suspended
> above
> the microtome. our resources did not stretch that far in those days
> (mid
> 70's). Once you have your sections, we had to use a starch based
> adhesive
> which was added to the slide and sections floated directly onto the
> pool of
> adesive. The trick was to ensure one end of the ribbon overlapped the
> end
> of the slide so that after the short period of time the sections took
> to
> expand and de-crease, the slide could be tipped allowing the adhesive
> to
> run away leaving a nice ribbon on the slide. The rest was easy!!
> Having read all of this, it comes as no surprise that my advice is to
> try
> every other option for getting what you want first.
> Best of luck.
> Steve
>                       Rebecca Nishi 
>                       Sent by:                               To:
>                       histonet-bounces@lists.utsouth         cc:
>                       western.edu                            Subject:
> [Histonet] Mouse and rat injured spinal cord - polyester wax
>                       04/05/2004 16:19
> Has anyone used polyester wax embedding for mouse or rat injured
> spinal
> cord. We would like to use a low melt wax instead of paraffin or
> plastic to
> preserve some of the antigens we are interested in, but we also are
> interested in doing stereology, so we want consistent and a complete
> set of
> sections. Also, the injured area poses many problems for sectioning.
> Does anyone have any tips for cutting and staining with this wax? I am
> going
> to use a rotary microtome.
> Thanks Rebecca
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