Microtome Knives in Histology

Microtome Knives

• Microtome knives are designed according to the tissue to be sectioned and the embedding medium.
• The choice of microtome knife is the greatest single factor in making good sections.

Types of Microtome Knives

• Metal microtome knives: made of standard steel and razor blade.
• Non-metal microtome knives: made of glass and diamond.
• Disposable blades: produce high-quality sections, have replaced conventional microtome knives, and provide a sharp edge for cutting 2-4μm thick sections.

Plano Concave Knife

• One side of the cutting surface is flat, and 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.
• Suitable for sledge and rotary microtomes.

Biconcave Knife

• Classical knife shape with concavity on both sides.
• Introduced by Heiffor.
• Suitable for rocking microtomes and sledge microtomes.
• Length: 100-250mm.
• Less rigid and prone to vibration.

Wedge Knife

• Can be 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

• A wedge knife with a steep cutting edge.
• Used for hard objects like undecalcified bone.
• Has a detachable handle that can be screwed onto a holder.
• The wedge knife is stable for a long time.
• Requires more force to achieve a cut.
• Available in varying lengths: 80mm for freezing microtomes and 240mm for base sledge microtomes.