OTF 5000/HS/LS-001/2/3/4 Iss 4 June 2012
30
• freezing technique too slow
• cutting temperatures too warm/cold
• specimen not equilibrated to chamber temperature
• specimen dehydrated
• knife not sharp enough
• cutting motion too fast or uneven
• knife tilt angle too high/low
Excessive compression of sections:
• knife not sharp enough
• knife tilt angle too high
• knife surfaces frosted or debris built up
• anti-roll plate frosted, too warm or incorrectly adjusted
• freezing technique too slow
• cutting temperature too warm
Uneven thickness across section:
• clamping screws too loose
• specimen loose in holder
• specimen was not trimmed correctly
• knife not sharp enough
• knife edge too thin
• cutting motion uneven
Vertical score marks on sections:
• knife edge nicked or chipped
• knife faces have built up debris or frost
• anti-roll plate edge damaged
• anti-roll plate surface has debris or frost built up
• tissue contains hard, fine particles (e.g. bone fragments)
NB: When removing frost and debris always brush up the knife, never down or along.
Sections curl over anti-roll plate:
• anti-roll plate too low
Section curl under anti-roll plate:
• anti-roll plate at too large an angle to knife
Sections curl under and stick to anti-roll plate:
• anti-roll plate too warm, greasy
Sections curl after lifting anti-roll plate:
• anti-roll plate at too large an angle to knife, movement too quick, delay in collecting
sections, static electricity present
Sections fail to flatten and pass down knife:
• anti-roll plate too warm, greasy or misaligned
• knife surface has built up frost or debris or is too warm
NB: To remove static electricity use an anti-static brush or gun. The main area of static
electricity build-up is on the anti-roll plate.
3.7 CUTTING TEMPERATURES
Standard textbooks on histological technique give tables of recommended cutting temperatures
for different tissues. However, in most cases, the following guidelines will prove adequate.
3.7.1 FRESH, UNFIXED TISSUE
Most soft tissues will cut at -18ºC to -20ºC. Fatty tissue, such as breast lumps, will need lower
temperatures, -25ºC or colder. Brain and spinal cord cut best at warmer temperatures, e.g.
minus 12ºC.
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