Microtomy: Troubleshooting Flashcards
Problems in tissue cutting: (7)
Compressed, Wrinkled or Jammed Sections
Skipping of Sections
Grooved, Scored, Smeared and Deformed Sections
Scratches, Lines, and Splits
Brittle and Shattered Sections
Failure to Form Ribbons
HOLES IN THE SECTIONS
Causes for Compressed, Wrinkled or Jammed Sections
Dull knife/blade edge
Too little knife/blade tilt
Rapid cutting
Warm room
Troubleshooting causes of Compressed, Wrinkled or Jammed Sections:
Dull knife/blade edge
Too little knife/blade tilt
Rapid cutting
Warm room
Resharpen the knife
Replace the blade with a new one
Increase the tilt of the blade
Decrease cutting speed
Change the room temperature Cool the block in ice water
Causes for Skipping of Sections
Very Large blocks Blocks with hard regions Materials not properly harden
Dull knife/blade
Too much tilting of the knife which scrapes of the section instead of cutting it
Worn out microtome (lack of lubrication and not in adjustment)
Troubleshooting for Skipping of Sections:
Very Large blocks Blocks with hard regions Materials not properly harden
Dull knife/blade
Too much tilting of the knife which scrapes of the section instead of cutting it
Worn out microtome (lack of lubrication and not in adjustment)
Soften the block:
• Soak the block in a bowl with ice water for 30
minutes to 1 hour
• Press the surface of the block with gauze soaked in
ice water for 1 minute before cutting
Resharpen the knife
Replace blade with a new one
Adjust the knife/blade so that the clearance angle between the cutting facet of knife and specimen is correct
Ensure that the microtome is in good working condition (routine maintenance)
Checked by the manufacturer
Causes for Grooved, Scored, Smeared and Deformed Sections
Dull knife/blade edge
Too warm room
Troubleshooting for Grooved, Scored, Smeared and Deformed Sections:
Dull knife/blade edge
Too warm room
Resharpen the knife/blade Replace knife/blade with a new one
Change the room temperature Cool the block in ice water
Causes for Scratches, Lines, and Splits
Defects or nicks in the knife/blade edge
Dirt/calcium, bone or other hard particles present in the block
Too much knife/blade tilt
Dirty knife/blade edge
Tissue too hard for paraffin
Troubleshooting for Scratches, Lines, and Splits:
Defects or nicks in the knife/blade edge
Dirt/calcium, bone or other hard particles present in the block
Too much knife/blade tilt
Dirty knife/blade edge
Tissue too hard for paraffin
Change blade Resharpen knife
- Check the tissue from foreign bodies the remove carefully to avoid damaging the tissue
- Refilter dirt in paraffin
- Decalcify the tissue
Decrease the tilt of the knife/blade
Clean the knife/blade edge
Use celloidin-embedding materials or soak in water to soften
Causes for Brittle and Shattered Sections
Incomplete dehydration or clearing
Incomplete infiltration of soft and mushy tissue
Too long in paraffin bath or too hot bath
Troubleshooting for Brittle and Shattered Sections:
Incomplete dehydration or clearing
Incomplete infiltration of soft and mushy tissue
Too long in paraffin bath or too hot bath
Rehydrate the block:
1. Shave the block to expose th etissue
2. Soak the block in tap water for a few hours
3. If still cannot be cut, leave the block in tap water
overnight
Reinfiltrate tissues with paraffin and re-embed
Try chloroform or toluene instead of xylene
Causes for Failure to Form Ribbons
Paraffin is too sticky (not enough plastic) or too hard (too high melting point)
Dull knife/blade edge
Too much knife/blade tilt
Too high or low room temperature
Troubleshooting for causes of Failure to Form Ribbons:
Paraffin is too sticky (not enough plastic) or too hard (too high melting point)
Dull knife/blade edge
Too much knife/blade tilt
Too high or low room temperature
- Lubricate the microtome with oil
- Change the microtome blade
- Check the angle of microtome
- Cut a blank or empty block
*Try to freeze the block the cut again
*Choose a paraffin with a lower melting point
Resharpen the knife
Replace the blade with a new one
Decrease the tilt of the blade
Change the room temperature
Causes of HOLES IN THE SECTIONS
Block positioned too aggressively
‘
Small flecks of tissue removed from the block
Excessive dehydration or improperly processed tissue
Troubleshooting for the causes of holes in the sections:
Block positioned too aggressively
‘
Small flecks of tissue removed from the block
Excessive dehydration or improperly processed tissue
Position the block less aggressively with smaller micrometer advances of the block for each removed sections
If there is sufficient tissue in the block, cut and discard ribbons until the holes disappear
Expose the tissue, then soak the block in ice water or with wet piece of cotton before sectioning
