RE: WHERE ARE THE CO2 MICROTOMES?
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|From:||"Molinari, Betsy" <BMolinari@heart.thi.tmc.edu>|
Do you mean throw away specimens or equipment?
> From: Simon Smith[SMTP:email@example.com]
> Sent: Wednesday, April 26, 2000 11:15 AM
> To: Histonet (E-mail)
> Subject: RE: WHERE ARE THE CO2 MICROTOMES?
> 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
> the thing siezed solid to replace the lubricant with low temperature
> 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
> it is.
> I have another semi off-topic question; do histologists ever throw
> away? I have noticed this inability to part with anything in the
> of the histologists I respect.
> Simon Smith B.Sc. AIBMS
> Supervisor, Laboratory Resources
> Skeletech, Inc.
> 22002 26th Ave SE, Suite 104
> Bothell WA 98021
> Voice: (425) 424 2663 Fax: (425) 424 2600
> E-mail: firstname.lastname@example.org
> -----Original Message-----
> From: J. A. Kiernan [mailto:email@example.com]
> Sent: Wednesday, April 26, 2000 7:37 AM
> To: Paulo Faria
> Cc: Histonet
> 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
> > 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
> 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
> 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:
> 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
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