sectioning epon

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From:Ian Montgomery <> (by way of histonet)
To:histonet <>
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>Date: Wed, 11 Nov 1998 16:46:00 -0800
>From: Cathy Mayton <>
>Subject: sectioning epon
>MIME-version: 1.0
>Fellow histonetters,
>I have been trying to section epon blocks containing an artery with a
>tungsten-carbide knife.  My sections appear cloudy at 3-6 microns.
	Cloudy appearance is just the same as thin trimming cuts when
preparing a block for ultrathinning. Look at the sections in a scanner -
	How big is the artery, would it cut more easily with a triangular
glass knife on an ultrotome. A good glass knife should cut 6Ám easily.
Ralph knives might help but don't expect a long life.
	If you must usde a tungsten carbide try wetting the face of the
block and the knife with 70% alcohol before each cut. Lift the section on a
alcohol soaked brush the flick onto surface of floating out bath.
Difference in surface tensions helps to flatten section.

>Does epon have to sectioned thinner than 3 um and can it only be sectioned
>with glass knives.
	Epoxy resins prefer thin sectioning. I use glass for semi-thin
(1-2Ám) and diamond for ultrahin.
>Also, what is the best way to dry the sections.  So far the literature I
>have says room temp over night.  What is the concensus?
	Mount sections on coated slides and dry on a hotplate.

> I also gleened from the literature that H&E cannot be done on epon sections.
	H&E on epoxy resin is a bummer and not worth bothering about. Nasty
corrosive chemicals and such. All the standard EM texts are full of recipes
for methylene and toluidine blue mixtures. My own favourites are
Pasyk,S., Bartok,W. & Rabry,A. 1989. Stain Technol. 64 (3) 149.
Polychrome staining of epoxy semithin sections using cacodylate as a stain
	The authors use the stain at 100-150C, I prefer RT.
Ito,S & Winchester,R.J. 1963. J. Cell Biol. 16. 541-577.
The fine structure of the gastric mucosa of the bat.
	This is a mixture of toluidine blue and pyronine Y. Gives lovely
shades of light purple/blue.
>The block polymerized well and contains no bubbles.  The block is
>sectioning easily other than the sections appear cloudy and not clear like
>GMA or MMA sections.  Any help would be appreciated.
>Cathy A. Mayton
>Wasatch Histo Consultants, Inc.

Dr. Ian Montgomery,
West Medical Building,
University of Glasgow,
G12 8QQ,
Tel: 0141 339 8855 Extn. 6602.
Fax: 0141 330 4100.

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