RE: WHERE ARE THE CO2 MICROTOMES?
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|From:||Jill Songer <firstname.lastname@example.org>|
|To:||Simon Smith <email@example.com>, "Histonet (E-mail)" <firstname.lastname@example.org>|
I think the inability for histotechs to part with "stuff" has something to
do with having to fight so dang hard to get the "stuff" in the first place.
Hey, you never know when you are going to need those lead L's.
At 09:15 AM 4/26/2000 -0700, Simon Smith wrote:
>We had two of them when I worked at the London Hospital back in Blighty. We
>found both of them in dumpsters when the anatomy department had a clear out.
>We used one of them once to cut serial 100um sections of unfixed human
>cartilage and subchondral bone. To do this we clamped it to a shelf in the
>walk in -20 freezer, let the temperature equilibrate, then removed it when
>the thing siezed solid to replace the lubricant with low temperature lube.
>Once set up it worked pretty well, you put on your skiing gear, go in, cut a
>few sections, come out, warm up, go back in.
>I wonder where it is now? I would guess either in the dumpster or where we
>left it surrounded by a group of puzzled biochemists wondering what the hell
>I have another semi off-topic question; do histologists ever throw anything
>away? I have noticed this inability to part with anything in the majority
>of the histologists I respect.
>Simon Smith B.Sc. AIBMS
>Supervisor, Laboratory Resources
>22002 26th Ave SE, Suite 104
>Bothell WA 98021
>Voice: (425) 424 2663 Fax: (425) 424 2600
>From: J. A. Kiernan [mailto:email@example.com]
>Sent: Wednesday, April 26, 2000 7:37 AM
>To: Paulo Faria
>Subject: Re: WHERE ARE THE CO2 MICROTOMES?
>On Tue, 25 Apr 2000, Paulo Faria wrote:
>> ... Where are the old CO2 microtomes? I thought
>> that before cryostats were readily available they were popular. Is that
>> true? Where are they?
> One of them, made by Leitz, is in my lab. It's at least 40 years old,
> has served me well for the last 27, and is still in regular use.
> Opinion: For getting thick sections of formaldehyde-fixed organs (and
> I mean FIXED, at least overnight and preferably for a week), you can't
> beat a CO2 freezer. Unless you're supremely skilful you can't get
> serial sections; for this you need accessories that maintain the
> temperature of the chuck, either by circulating cold alcohol through
> its innards or by using a Peltier-effect device (which needs
> circulating tap water to carry the heat away from its "hot"
> thermocouple junctions).
> A pathologist examining a frozen section from this traditional
> instrument must be able to evaluate sections very much thicker than
> the 4 to 7 um of routine paraffin histology. The screw advance
> on a typical CO2 freezer is calibrated from 0 to 100 um, and you
> can waggle the handle (moving the blade) to do double or treble
> increments of thickness, but unless you can make use of occasional
> lucky scraps don't expect anything thinner than about 20 um. A
> freezing microtome is at its best with sections that are nominally
> 40 to 80 um thick. The real thickness is variable, as is obvious
> at a glance to anyone who uses one.
> Cryostats offer many advantages over the freezing microtome: thinner
> sections; fixation is optional, etc etc. There are nevertheless
> plenty of circumstances when thicker sections are more informative
> than thin ones. It isn't easy to cut an 80 um section of anything,
> fixed or unfixed, in a cryostat.
> Another good thing about freezing with carbon dioxide is that
> it's fast, and ice crystal holes are rarely visible in the
> Perhaps some will disagree about these perceived virtues of the
> CO2 freezing microtome!
> John A. Kiernan,
> Department of Anatomy & Cell Biology,
> The University of Western Ontario,
> LONDON, Canada N6A 5C1
Jill Songer HT (ASCP)
Anatomic Pathology Supervisor
Veterinary Medical Teaching Hospital
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