Microtomy of Paraffin-Embedded Tissue

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Author: Diana Harrington, BS, HT(ASCP)
Reviewer: Carla Shoffeitt, MSM, HT(ASCP)

This course will identify the tools, processes, techniques, and problems associated with producing quality tissue slides. Essential microtomy skills are reviewed, with a focus on improving the quality and integrity of the tissue slide. Troubleshooting skills for commonly encountered microtomy problems and artifacts are also discussed.

Continuing Education Credits

Objectives

  • Identify instruments and tools essential for successful paraffin sectioning.
  • State the most common factors that directly affect the quality of microtomy.
  • Summarize an organized approach to the process of sectioning tissue blocks that focuses on improving the quality and integrity of the tissue slide.
  • Compare various cutting protocols for different tissue types and sizes.
  • Discuss proper slide drying and preparation for deparaffinization.
  • List the various hazards associated with microtomy.
  • Identify and troubleshoot problems and artifacts associated with the flotation bath, paraffin block, or microtome.

Course Outline

  • Introduction to Microtomy
      • Introduction to Microtomy
      • Introduction to Microtomy, continued:
      • Successful microtomy is dependent on tissue fixation, processing, and embedding.
      • Although a tissue section may be flawless, which of the following factors may render it undiagnosable?
      • Instrumentation for Microtomy: Rotary Microtome Parts
      • The safety lock, most often located on or near the advancement wheel, should be used whenever the microtomist is NOT actively sectioning paraffin bloc...
      • Instrumentation for Microtomy: Knife/Blade
      • Low-profile blades require more frequent sharpening, unlike the high-profile blades.
      • Instrumentation for Microtomy: Knife Angles
      • The bevel angle can be adjusted on a microtome by moving the knife tilt/knife holder to an angle between 3-8°.
      • Instrumentation for Microtomy: Flotation Bath
      • Instrumentation for Microtomy: Flotation Bath Artifacts and Adhesives
      • A laboratory uses paraffin with a melting point of 56° C. What is the optimal temperature range for the water bath when floating these paraffin s...
      • Instrumentation for Microtomy: Precision Tools
      • All tools used to transfer ribbons or pick up paraffin sections have the potential to introduce artifacts into the tissue and increase the risk of con...
      • Instrumentation for Microtomy: Glass Slides
  • The Process of Sectioning Paraffin-Embedded Tissue
      • Common Factors Affecting Sectioning Quality
      • Washboarding (undulations) introduced into tissue sections is MOST often caused by an unstable work surface or microtome parts that are not properly t...
      • Process of Sectioning Paraffin Tissue
      • A histotechnology student attempts to coarse face a bone sample embedded in a paraffin block. The bone is very difficult to face and is beginning to c...
      • Special Sectioning Protocols for Various Tissue Types and Sizes
      • A pathologist orders a Congo red (amyloid) stain on a skin sample. At which thickness should the tissue block be cut for optimal stain results?
      • Proper Slide Drying for Paraffin-Sectioned Slides
      • A histotechnology student manually deparaffinizes and performs hematoxylin and eosin (H&E) stains on a dozen tissue slides, only to discover that ...
  • Hazards Associated with Microtomy
      • Microtomy and Injury Prevention: Mechanical Hazards
      • Microtomy and Injury Prevention: Biological and Ergonomic Hazards
      • Think about the mechanical and ergonomic hazards associated with microtomy. Drag and drop the actions that would either be a potential mechanical or e...
      • Injury Prevention: Good Laboratory Practice
      • When performing various microtomy procedures, chemical exposure should be the microtomist's primary hazard concern.
  • Troubleshooting Microtomy Problems
      • Troubleshooting Common Microtomy Problems
      • Many microtomy problems have several sources that require consideration in order for the issue to be resolved.
  • Artifact Characteristics, Causes, and Corrections
      • Microtomy Artifacts: Causes and Corrections
      • Microtomy Artifacts: Causes and Corrections, continued.
      • The pathologist requests a recut on a small intestine biopsy block because the chatter is interfering with his diagnosis. What should the histotechnol...
  • References
      • References

Additional Information

Level of instruction: Basic
 
Intended audience:  Clinical laboratory histotechnologists, histotechnicians, and other medical laboratory personnel who have an interest in this subject matter. This course is also appropriate for histology and clinical laboratory science students, pathology residents, and practicing pathologists.  
 
Author information: Diana Harrington, BS, HT(ASCP) is a histotechnologist at The Dermatology Center of Indiana. Since graduating from Indiana University, she has worked in various hospital laboratories as a medical technologist and histotechnologist. Her experience led her to teach IU students as a Clinical Education Supervisor and create the Histotechnology Program as Program Director for Keiser University in Florida.
 
Reviewer information: Carla J. Shoffeitt, MSM, HT(ASCP) is the System Director of Anatomic Pathology for Emory Healthcare in Atlanta, Georgia. She holds a Master of Science Degree in Healthcare Management as well as a Bachelor of Science degree in Biology from Troy University, Troy, Alabama. She is certified as a Histotechnician and has 29 years of experience in the field of Histology.
 
Course description:  The microtomy of paraffin-embedded tissue has been an essential component of microscopy for over a century. This course will identify and discuss the tools, processes, techniques, and problems associated with producing quality tissue slides, including necessary troubleshooting skills. 

This course is part of:
Automated Rotary Microtome
Knife lines in tissue from a damaged knife.
Undulations seen in a tissue section.
Block edges are not in line with the blade.
Venetian blind effect
Modern Rotary Microtome edit advancement handwheel 400