Paraffin Impregnation Troubleshooting in Histology

Paraffin Impregnation Troubleshooting in Histology

This quiz troubleshoots common issues in paraffin impregnation, a crucial step in histology specimen preparation. It identifies causes and solutions to problems like contaminated wax, incomplete impregnation, and inadequate cooling.

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Answer from memory first, then review the rationales and revisit weak areas from this set.

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Quiz18 Questions
Study Notes1 Note
Podcast1 Episode

List of Questions18 questions
  1. Question 1
    • Paraffin block is warm and soft
    • Microtome set screw is loose
    • Knife is not parallel to the block
    • Tilt of knife is too vertical
  2. Question 2
    • Insufficient paraffin impregnation
    • Contaminated wax
    • Tough keratin component of certain tissues
    • Incomplete clearing
  3. Question 3
    • Re-embed in freshly filtered wax
    • Hone and strop the knife
    • Re-trim the block
    • Readjust knife and block
  4. Question 4
    • Prolong the clearing process up to 12 hours
    • Change the paraffin at least once before blocking
    • Use a different type of wax
    • Increase the temperature of the embedding oven
  5. Question 5
    • Knife edge is coated with paraffin
    • Tilt of knife is too great
    • Blocks are too hard
    • Microtome set screw is loose
  6. Question 6
    • It is a poor fat solvent
    • It is too expensive
    • It is too toxic
    • It is not available
  7. Question 7
    • 10% formalin
    • Distilled water
    • Absolute ethanol
    • 4% aqueous phenol
  8. Question 8
    • Coat horizontal edges of the block with wax of lower melting point
    • Reduce the tilt of the knife
    • Re-trim the block
    • Soften the blocks in detergent or phenol
  9. Question 9
    • To ensure complete fixation
    • To prevent contamination
    • To facilitate easy reagent action
    • To reduce the cost of reagents
  10. Question 10
    • Bubble or dirt formed in the embedding medium
    • Knife edge is dull
    • Tilt of knife is too great
    • Blocks are too large
  11. Question 11
    • Cool/change the room temperature or cool the block in ice water
    • Trim the block edges until they are parallel
    • Reduce the tilt of the knife
    • Re-sharpen the knife using a knife back or automatic knife sharpener
  12. Question 12
    • Isopropanol
    • Distilled water
    • Methanol
    • Acetone
  13. Question 13
    • Insufficient fixation
    • Overheated paraffin oven
    • Inadequate dehydration
    • Incomplete removal of water during dehydration
  14. Question 14
    • Tissue becomes brittle and hard
    • Tissue shrinks away from wax when trimmed
    • Insufficient dehydration and incomplete clearing and impregnation
    • Tissue is soft when block is trimmed
  15. Question 15
    • Insufficient clearing
    • Presence of airholes in the tissue
    • Tissue is too soft
    • Overheated paraffin oven
  16. Question 16
    • Prolonged dehydration
    • Prolonged fixation
    • Soaking in a small dish or bowl containing water with detergent
    • Repeat dehydration with absolute alcohol then clear again
  17. Question 17
    • Inadequate processing of fatty tissues
    • Moisture in the paraffin block
    • Overheated paraffin oven
    • Insufficient dehydration
  18. Question 18
    • Tissue is soft when block is trimmed
    • Clearing agent turns milky as soon as tissue is placed in it
    • Insufficient clearing and impregnation
    • Tissue shrinks away from wax when trimmed