OTF 5000/HS/LS-001/2/3/4 Iss 4 June 2012
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there is not an accumulation of rime present on the underside and leading edge of the
anti-roll plate. Care must be taken when using Cryospray 134. The risk of creating an
aerosol of potentially infectious tissue particles must be borne in mind.
5 If the section is skewing, this is a sign that the anti-roll plate is not parallel to the edge of
the knife. Remember also that the angle of the underside of the anti-roll plate must be
parallel to the facet of the knife (but just a little larger for the best results). If the angle is
too large then the section will curl. If the angle is too small then the section will crumple.
6 If there is any doubt that the temperature of the microtome or cryostat chamber is not at
the right temperature, be patient and wait for a while until the temperatures equalise.
7 For other problems follow the advice in section 3.6 below.
3.6
FROZEN SECTIONING - A PROBLEM SOLVING GUIDE
Cutting good frozen sections requires skill and practice, and some tissues are particularly
difficult. In all cases the quality of the result depends on a number of factors.
The notes which follow deal with the more commonly encountered difficulties, and suggest a
systematic approach to problem solving.
3.6.1 SOLUTIONS - CHECK LIST
First check all the basic factors:
Specimen
•
was it frozen badly?
•
has it equilibrated to chamber temperature?
•
has it become loose on the specimen holder?
•
is the specimen holder tightly clamped?
•
is the orientation lever locked?
•
has the specimen dehydrated?
Knife
•
has it become dull?
•
is it nicked or chipped?
•
is the knife tilt angle incorrect?
•
is the knife loose?
•
is there a build-up of frost or debris on the knife?
Anti-Roll Plate
•
is it set too high/low?
•
is the angle to the knife too wide/narrow?
•
is it parallel to the knife?
•
is it frosted/too warm?
•
is it damaged? (See section 2.2.8).
General Factors
•
is the chamber temperature appropriate to the specimen (or specimen temperature
control, where fitted)?
•
is the cutting motion too fast/slow/uneven?
•
has the microtome reached the end of its travel?
•
is the section thickness setting appropriate?
3.6.2 SPECIFIC PROBLEMS
Thick/thin sections, intermittent failure to cut:
•
knife not sharp enough
•
knife tilt angle too high/low
•
clamping screws too loose
•
specimen loose on holder
•
cutting temperatures too warm/cold
•
anti-roll plate adjusted too high
•
tissue expansion due to block warming up
Sections crumbling or not forming:
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