microtomy troubleshooting Flashcards
crooked or uneven ribbons
edges of knife and block are not parallel
the four sides of the block are not trimmed parallel
the knife edge is dull
impurities in the wax
vary densities in the tissue
block not evenly chilled
block unevenly sectioned
block holder not adjusted to parallel the blade
holes in the section
block is faced too aggressively
improper processing ( excessive dehydration)
sections will not ribbon
- wax is too hard
- knife clearance angle too great
- dirty knife edge
- wax surface or knife too cold
lifting of section from blade as block is raised
knife clearance angle too fine
blunt knife or dirty knife edge
dirty underside of block
washboarding or undulations in the sections
tough tissue such as uterus
overfixed tissue
worn microtome
not enough wax placed on top of cassette when embedding
clamps are loose
blockholder shaft is overextended ( neck too far out)
clearance angle is too large
chatter or microscopic vibration
over dehydration
dull blade
clearance angle too large
cutting too fast
thick or thin or skipped sections
loose knife or loose block
block too large for microtome
clearance angle too small
tissue or wax excessively hard
wrinkled, compressed or jammed sections
blunt or dirty knife
warm block / knife
clearance angle too small
cutting too fast
micrometer set too thin for wax hardness
loose knife
ribbons split vertically or scratch line appear
small nicks in the knife edge
knife clearance angle too great
hard material embedded in the wax
- dirt , grit, crystals, talc
hard material in the tissue
- calcium, crystals, sultures
dirt on the knife edge
scratched by calcium deposit
- if the clearance angle is correct & blade is not damaged - place faced block in acid to dissolve calcium
sections crumble or tear
tissues incompletely dehydrated
tissue has not cleared properly
paraffin wax denatured - excessive heating
blunt knife
wrong melting point wax used for the conditions- wax too soft
wax has crystallized from slow cooling
wax is contaminated with clearing scent or water
sections roll up on cutting
blunt knife
knife clearance angle too great
micrometer set too great
wrong melting point wax for the conditions
sections disintegrate on water bath
water bath temp too high
wax contaminated with clearing agent
obtaining wrinkle free sections
practice
patience
alcohol bath before flotation
chilling or warming surface of block
adding water to block face
brayer
