Microtome: A Device for Cutting Thin Slices

Study Notes

A device used to cut extremely thin slices of material, known as sections, for observation under transmitted light or electron radiation.
Uses steel, glass, or diamond blades depending on the specimen being sliced and the desired thickness of the sections.

Steel blades: used for preparing sections of animal or plant tissues for light microscopy histology.
Glass knives: used for slicing sections for light microscopy and for slicing very thin sections for electron microscopy.
Diamond knives: used for slicing hard materials such as bone, teeth, and plant matter for both light and electron microscopy.

Used to prepare thin sections for materials such as bones, minerals, and teeth.
Sections can be made thin enough to section a human hair across its breadth, with section thickness between 50 nm and 100 μm.

The earliest form of microtomy involved freehand sectioning of fresh or fixed material using a sharp razor.

Sledge microtome: used for preparing large samples, such as those embedded in paraffin for biological preparations, with a typical cut thickness of 1-60 μm.
Rotary microtome: used for hard materials, with a typical cut thickness of 1-60 μm, and can achieve semi-thin sections with a thickness of as low as 0.5 μm.
Cryomicrotome: used for cutting frozen samples, with a typical cut thickness of semi-thin samples, and requires controlled sample and knife temperatures.
Ultramicrotome: used for preparing extremely thin sections, with a typical cut thickness of 40-100 nm for transmission electron microscopy, and uses diamond or glass knives.
Vibrating microtome: uses a vibrating blade to cut with less pressure, and is used for difficult biological samples, with a typical cut thickness of 30-500 μm for live tissue and 10-500 μm for fixed tissue.
Saw microtome: used for hard materials such as teeth or bones, with a recessed rotating saw, and a minimal cut thickness of approximately 30 μm.
Laser microtome: uses contact-free slicing, prior preparation of the sample is not required, and can be used for very hard materials, with a typical cut thickness of 10-100 μm.