Podcast
Questions and Answers
What should be done if the surfaces of the block are not parallel?
What should be done if the surfaces of the block are not parallel?
Re-trim the block.
How can you address sections failing to form properly due to a knife being too tilted?
How can you address sections failing to form properly due to a knife being too tilted?
Reduce the tilt of the knife.
What action should be taken if sections roll up during cutting?
What action should be taken if sections roll up during cutting?
Sharpen the knife.
If the paraffin wax is too hard, what remedy can be applied?
If the paraffin wax is too hard, what remedy can be applied?
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What needs to be done if the ribbon is curved instead of straight?
What needs to be done if the ribbon is curved instead of straight?
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What should you do if the knife edge is dirty during the cutting process?
What should you do if the knife edge is dirty during the cutting process?
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What should you do if the sections are too thin?
What should you do if the sections are too thin?
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What is the remedy for a paraffin block that is warm and soft?
What is the remedy for a paraffin block that is warm and soft?
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What should you do if the microtome set screw is loose?
What should you do if the microtome set screw is loose?
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How can you correct the tilt of the knife if it is too vertical?
How can you correct the tilt of the knife if it is too vertical?
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What might cause sections to be squashed or have a width less than that of the block?
What might cause sections to be squashed or have a width less than that of the block?
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What should you do if bubbles or dirt are formed in the embedding medium?
What should you do if bubbles or dirt are formed in the embedding medium?
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What could cause a hole to form in the section?
What could cause a hole to form in the section?
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If sections of unequal thickness are produced, what is one possible action to take?
If sections of unequal thickness are produced, what is one possible action to take?
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What can you do to combat static electricity that may cause sections to adhere to the knife?
What can you do to combat static electricity that may cause sections to adhere to the knife?
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If the knife edge is dull and causing issues, what should you do?
If the knife edge is dull and causing issues, what should you do?
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What should you do if scratches are seen on the sections during cutting?
What should you do if scratches are seen on the sections during cutting?
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What is one reason for resistance felt on the lower part of the section during cutting?
What is one reason for resistance felt on the lower part of the section during cutting?
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What problem is indicated when horizontal or parallel lines appear as furrows across the section?
What problem is indicated when horizontal or parallel lines appear as furrows across the section?
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What action should be taken if the knife makes a hard metallic scraping sound when cutting?
What action should be taken if the knife makes a hard metallic scraping sound when cutting?
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If the knife or block holder is loose, what adjustment should be made?
If the knife or block holder is loose, what adjustment should be made?
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What should be done if frozen tissue chips into fragments when cut?
What should be done if frozen tissue chips into fragments when cut?
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What is a potential remedy when paraffin is too soft during the sectioning process?
What is a potential remedy when paraffin is too soft during the sectioning process?
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What might indicate that freezing is inadequate during tissue processing?
What might indicate that freezing is inadequate during tissue processing?
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Study Notes
Faults in Microtome Sections
- Sections fail to form ribbon: Surfaces and edges of the block are not parallel, horizontal surface not parallel to knife, paraffin wax too hard, knife tilted too much, sections too thick, knife dull, or dull spot on knife. Remedies include re-trimming the block, readjusting the block, Coating with lower melting point wax, reducing tilt, adjusting thickness, honing and stropping the knife, or cleaning the knife.
- Sections roll up on cutting: The knife is dull, knife's tilt is too great, the knife's edge is dirty; solution is adjusting/cleaning, or throwing away the knife.
- Ribbon is curved, crooked or uneven: Knife is blunt or dull, edges of the block are not parallel, knife not parallel to block, paraffin is impure. Remedies are adjusting knife for uniform edge, re-trimming the block, or re-adjusting the knife & block.
- Sections are compressed, wrinkled, or jammed: Knife is dull or dull/blunt spot, paraffin is soft, knife edge coated in paraffin, sections too thin, microtome set screw loose or tilt of knife too vertical; solutions are sharpening knife, cooling or cooling to firm the block, cleaning the knife, readjusting the thickness of sections, or tightening the screw.
- Sections are squashed: Bevel of knife lost due to incorrect sharpening, solution is re-sharpening with knife back/automatic sharpener.
- Hole formed in the section: Bubbles or dirt in the embedding medium, hard spot in tissue potentially calcium; solution is re-embedding in filtered wax if necessary.
Other Section Issues
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Sections of unequal thickness: Knife tilt too great, bevel not cleared, block holder is loose, or blocks too large or too hard; remedies are reducing tilt, tightening screws, or cutting blocks into smaller pieces.
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Sections adhere to the knife or other machine parts: Static electricity due to low humidity, knife edge is dirty or dull, or bad embedding medium; remedies are breathing out on the block and knife, cleaning the knife edge, sharpening knife, or re-embedding.
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Ribbon is split or lengthwise vertical scratches: Nicks or damage on knife edge, dirty embedding medium. Cleaning knife edges and sharpening is recommended.
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Sections are tilted from the knife: Knife is dull or room temperature is too warm. Solution is sharpening, cooling paraffin, or reducing tilt.
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Resistance felt on lower part of section during cutting: Insufficient knife tilt, and paraffin block compressed against knife base. Solutions are increasing the tilt, or treating material with phenol during processing or collodion treatment.
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Furrows (chattering) seen (thin/thick zones): Knife edge too hard, knife is blunt, knife is not clamped properly, knife's tilt is too great. Solutions are sharpening the knife, adjusting the knife, reducing the tilt, checking clamping.
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Knife makes harsh metal scraping or ringing sound: Knife is blunt/not clamped correctly, knife's tilt is too great/slanted/too big, blade is too thin knife block holder is loose; remedy is readjusting the knife's tilt/position, checking clamping, and sharpening
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Frozen tissue crumbles and comes off the holder when cut: Freezing is inadequate or tissue frozen too hard. Tissue needs to be refrozen or warmed as needed.
Brittle or Hard Tissue Issues
- For brittle, or hard tissue Prolonged fixation, prolonged dehydration, prolonged clearing, prolonged paraffin infiltration, and overheated paraffin oven negatively impact tissue quality and should be avoided, if possible. Drying out of tissue before fixation can be beneficial. To remedy, tissue should be softened by soaking in a small dish with detergents, phenol, or Molliflex for better sectioning.
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Description
This quiz covers common faults encountered in microtome sections, such as issues with ribbon formation, section rolling, and uneven cutting. It explores the causes of these problems and the recommended remedies to ensure smooth microtomy processes. Test your knowledge and understanding of microtome techniques and maintenance.
