[Histonet] Methacrylate cuttting

[RCHIOVETTI <@t> aol.com]

In a message dated 8/9/2005 7:31:29 AM US Mountain Standard Time, 
abee <@t> pml.ac.uk writes:

> HELP!! To all of you this will probably be such an easy solution. My boss 
> is
> on annual leave for 3 weeks and has left me the task of practising cutting
> methacrylate sections at 3microns.
> 
> 

Amanda,

If you are using glass knives, are they the triangular type of knives, or the 
longer type of "Ralph" knives?  Are you using an ultramicrotome?  Or are you 
using a glass knife adapter on a regular rotary microtome?  And can you put a 
"boat" or a "trough" on the knife so it can hold a little water?

Methacrylate tends to be a little soft, and it's not uncommon to see the 
sections crumple and stick to the knife edge.  You could probably get better 
results if you could use the sectioning techniques that are used for electron 
microscopy.  These involve bringing water up to the knife edge, so the sections 
float onto the water surface as they are cut.  You can then retrieve the sections 
with a small wire loop or a hair mounted on a stick, and transfer them to a 
drop of water on a glass slide.

Also, using water during sectioning will help the sections "relax" and 
flatten out.  A lot of the methacrylates are hydrophilic, and you can actually watch 
them expand slightly as they come off the knife edge and float on the water 
surface.

If you were cutting slightly thicker, say around 5-8 microns, you might be 
able to *carefully* use a pair of fine-tip watchmaker's forceps or a hair and 
gently guide the sections down the knife as they are cut.  But this may not work 
at 3 microns thickness.

This may have been discussed previously on Histonet...I can'r remember for 
sure.  You can go to:
<www.histosearch.com>

and try searching the Histonet archives using words like:
sectioning methacrylate

Hope this helps!

Cheers,

Bob

Robert (Bob) Chiovetti, Ph.D.
The Microscope Works
Arizona's Microscopy Resource
132 North Elster Drive
Tucson, AZ 85710-3212 USA
Tel./Fax 520-546-4986
Member, Arizona Small Business Association - ASBA