Dear Beth,

I believe the problems you are having on sectioning fat are caused by one of
two problems with your cryostat.

Firstly, you need to be sectioning fat at around minus 30 deg.C. Rotary
microtomes very often get very tight at these temperatures and stop
advancing, if they are adjusted for the lower temperature ranges , then they
do not perform so well for the majority of tissues that are sectioned in the
minus 20 deg.C range. We have had a lot of experience with fitting many
types of rotary microtomes into our cryostats in the past and stopped doing
so due to this problem and now only supply them fitted with radial or rotary
rocking microtomes that work well through a full range of temperatures that
do not effect the performance of the microtome.

Secondly, due to the effect on the microtome at these temperatures, the
specimen holder is lowered in temperature for fatty tissue down to minus 30
deg.C. but the microtome, knife and anti-roll plate are still set for minus
20 deg.C. This causes problems as the sections warm up when they come into
contact with the knife and anti-roll plate and the sections cannot be
collected, we address this in our cryostats by setting the temperature in
the microtome chamber to minus 40 deg. and then setting the specimen holder
to any temperature say minus 8 to minus 38 deg.C. to suit the tissue
required for sectioning, it is also very useful when the correct temperature
for some tissues are difficult to find, as the temperature of the tissue can
be adjusted very quickly to determine the correct cutting temperature.

To overcome the problem, you will have to spray the specimen, knife &
anti-roll plate with a refrigerant spray (Cryospray) to get your fatty
sections.

Best Regards

Alan Bright

Bright Instrument Co.Ltd.
St Margarets Way
Huntingdon
PE18 6EB
England

Tel No:+44 (0)1480 454528
Fax No:+44 (0)1480 456031
Email: AlanBright@brightinstruments.com
Web Site: www.brightinstruments.com


-----Original Message-----
From: HistoScientific <histosci@shentel.net>
To: histonet@pathology.swmed.edu <histonet@pathology.swmed.edu>
Date: Tuesday, August 17, 1999 04:18
Subject: Frozen secioning fat tissue


>Histonetters,
>
>We just completed a study consisting of mouse fat.  This fat was taken
>from around such tissues as the uterus, heart, etc.  We used a cryostat
>made by Microm and had it set at everywhere from -18 to -35 degrees.  We
>left the tissue in the cryostat overnight and still no luck.  We could
>not get a section no matter how thick or thin we tried cutting them.  We
>then tried Histofreeze, still no luck.  To make a long story short, we
>ended up giving "fat smears".  We have never had problems with our
>cryostat and the techs that were working on this project had over a
>century of experience with frozens.  Maybe Instrumedics could have come
>to the rescue!
>
>Beth Poole
>Histo-Scientific Research Labs.
>107 Killmon Road
>P.O. Box 30
>Basye, VA  22810
>(540)856-2222
>histosci@shentel.net
>
>