Re: LR White

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From:"R.Wadley" <>
Date:Wed, 18 Aug 1999 08:45:16 +1000
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	Dear Jill,

	Yes you can (or least you could) get extra large gelatin capsules.  I
worked in a lab a couple of years ago that had drawers full of stuff dating
back to the 50's & 60's.  One of the many interesting items were gelatin
capsules ~2 cm dia x ~4.5 cm in length.  You might need to try a veterinary
supplier as these are the sort of things they try to persuade livestock to
swallow, to give them their medicine.

	LR White must be allowed to polymerise in the absence of oxygen, even BEEM
capsules are unsuitable because they are porous to O2.  As to making it
softer, LR White (if memory serves correctly) can be purchased as soft,
medium or hard.  I'm not sure but I think this can be further varied by the
amount of activator added to the new bottle when you recieve it.  This may
mean extended polymerisation times.

	I am assuming you are looking at cutting large sections (ie > 1 cm
square), even soft LR White may be too brittle.  You may have to consider
some other sort of resin, for eg Historesin if dehydration is OK, JB4, if
you don't want to do any dehydration (my favourite for research histo stuff).

	The other alternative is to get an adapter for you modern microtome head
that allows you to use a clamp, ie the microtme head that was used before
anybody thought of cassettes.  Then you can use much smaller capsules.
Depth will be a limiting factor here.

	Rob W.

At 10:12 08/17/1999 +0100, you wrote:
>                  I,ve been asked to produce an LR white embedded block of
>embryo chick head which  can be used for Magnetic resonance then cut on an
>ordinary microtome with a disposable blade or steel blade, serial sections
>of 4-5 microns.So  if anybody out there can give advice me any advice about
>the best way to go about this I would be  well pleased. I have the basic 
>method for processing but I need the LR White to be a bit softer than for 
>EM, I tried it in the oven without accelerator  using a metal mould
>but  to no avail.Can you get extra large gelatin capsules large enough to
>grasp in a microtome chuck head ?  Is this the best way to do this?  Thanks
>in anticipation.
>Jill McVee, Histologist, St. Andrews Uni. Scotland.

R. Wadley, B.App.Sc. M.L.S, Grad.Dip.Sc.MM
Laboratory Manager
Cellular Analysis Facility
School of Microbiology & Immunology
UNSW, New South Wales, Australia, 2052
Ph (BH) 	+61 (2) 9385 3517
Ph (AH)	+61 (2) 9555 1239
Fax 	+61 (2) 9385 1591

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