Microtomy Techniques and Types

Microtomy (Section Cutting)

• Microtomy is a technique for making thin slices of tissue specimens for microscopic examination.
• Thin slices are needed to allow light to pass through.
• Sections must be ≤ 1 cell thick.
• Sectioning is necessary for thick specimens that block light passage.
• Sectioning exposes internal structures of thick tissues for observation.

Types of Sectioning

Free-hand Sectioning

• Used for hard materials that can withstand a sharp instrument.
• No embedding is required.
• Skilled practitioners can achieve sections as thin as 10 µm.
• Method: Holding material, using a sharp razor that slides horizontally across a finger.
• Procedure:
  • Trim a piece of pith into a rectangular block.
  • Split the block vertically.
  • Position the material vertically and firmly hold it.
  • Hold the razor horizontally away from you, at pith level.
  • Slide the razor toward you.
  • Repeat until thin, complete sections are obtained.
  • Avoid oblique cuts.
  • Transfer sections to water on a watch glass.
  • Only select thin, complete sections for observation.

Serial Sectioning

• Objects are cut into a series of consecutive slices.
• Each slice is mounted on a slide.
• Used to reconstruct the structure of organs, tissues, or cells.
• Allows for studying vascular supply, cell organization, differentiation, and host-parasite relationships.
• Commonly uses a rotary microtome.
• Rotary microtome produces a ribbon of continuous sections.
• Sections are mounted onto slides in order.
• Example: Serial sections of a mouse brain.

Microtome

• A mechanical device for cutting thin slices of material, especially those that can't be sectioned freehand.

• Used to overcome the drawbacks of free-hand sectioning (non-uniform thickness, unable to make sections <10µm)

• Embeds the material in a supporting medium (wax, resin).

• Types:

  • Sledge Microtome
  • Rotary Microtome

Sledge Microtome

• The specimen remains stationary, and the knife moves.
• A heavy, clamped knife slides along a groove.
• Section thickness is adjusted by a graduated head.
• Cutting a section automatically positions the specimen for the next cut.

Rotary Microtome

• The knife is stationary, and the specimen moves.
• Used often in serial sectioning.

Explore the art of microtomy, a vital technique used for preparing thin tissue sections for microscopic analysis. This quiz delves into the importance of sectioning in revealing internal structures of specimens and covers different methods, including free-hand sectioning. Test your knowledge on the procedures and principles of microtomy.