Microtome Knives in Histology

Microtome Knives

• Microtome knives are modeled according to the tissue to be sectioned and the embedding medium, making them the greatest single factor for making good sections.
• Knives come in many shapes, sizes, and materials to fit certain microtomes and to cope with different degrees of hardness of tissues and embedding media.

Types of Microtome Knives

• Metal knives:
  • Standard steel
  • Razor blade
• Non-metal knives:
  • Glass
  • Diamond

Disposable Blades

• Produce consistently high-quality sections
• Have replaced conventional microtome knives
• Provide a sharp edge for cutting 2-4μm thick sections
• Made of high-quality stainless steel

Types of Microtome Knives (continued)

• Plano concave knife:
  • One side of the cutting surface is flat, the other is concave with different degrees of concavity
  • Extremely sharp but delicate
  • Used for cutting soft samples like nitrocellulose embedded tissues
  • The plane surface is closest to the tissue block
  • Used with sledge and rotary microtomes
• Biconcave knife:
  • Classical knife shape with concavity on both sides
  • Introduced by Heiffor
  • Used with rocking microtome and sledge microtome
  • Length: 100-250mm
  • Less rigid and prone to vibration
• Wedge knife:
  • Used in all types of microtomes to cut all types of materials
  • Both cutting surfaces are plane
  • Known as standard profile
  • Size: 100-350mm
• Tool edge/Chisel knife:
  • Wedge knife with steep cutting edge
  • Used for hard objects (undecalcified bone)
  • Has a detachable handle (to screw with holder)
  • Stable for a long time
  • Requires more force to achieve the cut
  • Varying lengths available (80mm for freezing microtome, 240mm for base sledge microtome)