Re: attaching MMA thin sections to slides

From:Karen Pawlowski

Hi Teri John,

It could be I have the wrong material in mind. I am talking about
methylmethacrylate, which we have always called MMA, in this case 
Spurrs. I don't know if PMMA is the same thing, but the original post
I got said MMA. GMA to me is glycolmethacrylate, such as JB-4. 

The specimens I do for MMA (Spurrs) are limited to about 1-2 mm in 
any direction. The JB-4 (GMA) sections can be much bigger and they 
can't be sectioned directly into a boat, as the blocks will pick up 
water. They are sectioned first, then placed on the surface of a large
boat and allowed to react before they are placed on a slide and heated
on a warm plate.  The hot plate that I use for Spurrs is too hot for 
the JB-4.

Setting the sections on a slant on the hot plate allows the section to 
dry down one side at a time instead of drying all of the sides first,
trapping a small bead of water under the section and causing the section
to dome-up, which eventually leads to major wrinkles when the water 
finally evaporates.

I hope this clarifies things a bit.

Karen

"Johnson, Teri" wrote:
> 
> What is the benefit of floating out sections on a slide versus rolling them with plastic and clamping them (besides being quicker)?  I tried floating out PMMA sections and found they wrinkled much more than flattening them with a roller. I didn't try the technique of using a hot plate.  In the technique below, the slides do not lay flat on the hot plate but are propped up so the water drains out from beneath the section?  And, is it ok to dry cut PMMA blocks?
> 
> Signed,
> 
> Teri Johnson (The PMMA novice)
> 
> Teri Johnson
> Managing Director Histology Facility
> Stowers Institute for Medical Research
> 1000 E. 50th St.
> Kansas City, Missouri  64110
> tjj@stowers-institute.org
> 
> -----Original Message-----
> From: Karen Pawlowski [mailto:kpawlow@swbell.net]
> Sent: Wednesday, February 12, 2003 9:00 AM
> To: Sarah Jones
> Cc: histonet@pathology.swmed.edu
> Subject: Re: attaching MMA thin sections to slides
> 
> Sarah,
> 
> We have good luck with 0.5 to 6 micron thin sections using the following
> protocol:
> 
> 1) section the 4-6 micron sections dry with a glass knife; or thinner
> sections with a glass knife equipped with a boat filled with distilled
> water
> 2) use a forceps for the dry-cut sections or a tapered wooden pick for
> the wet-cut sections to place them on a dome of distilled water on the
> Superfrost Plus slide
> 3) heat on a hot plate that is set a little less hot that that which
> would make the water on the slide boil (too hot to touch). Place an
> old glass knife on the hot plate so that the slide can be propped up
> on it at the frosted (handling) end.
> 4) let the water under the section evaporate and then wait 20 seconds
> before removing the slide from the hot plate and staining
> 5) stain with filtered toluidine blue, by placing drops of stain so
> they dome over the sections and placing the slide flat on the hot plate
> for 15-20 seconds. Don't let the stain boil or dry out.
> 6) tap off the stain and quick rinse in 3 changes of distilled water,
> one change in 70% ethanol and then one more change of distilled water
> and place the section back on the hot plate at an angle, over the old
> glass knife until dry
> 7) coverslip
> 
> We have had very good luck with this protocol, in fact we have none of
> the sections releasing even if we have to remove the coverslip and
> restain.
> 
> Good luck,
> 
> Karen Pawlowski, Ph.D.
> Research Scientist
> University of Texas at Dallas
> Dallas, Texas




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