Microtome in Microscopy

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.
Can produce sections thin enough to section a human hair across its breadth, with section thickness between 50 nm and 100 μm.

Earliest form of microtomy was the freehand sectioning of fresh or fixed material using a sharp razor.
With practice, sections could be made quite thin and translucent.

Sledge microtome:
- Typical applications: preparation of large samples, such as those embedded in paraffin for biological preparations.
- Typical cut thickness: 1-60 μm.
Rotary microtome:
- Typical cut thickness: 1-60 μm.
- Can be adapted for cutting hard materials, such as samples embedded in a synthetic resin, with a thickness of as low as 0.5 μm.
Cryomicrotome:
- For cutting frozen samples.
- Allows the preparation of semi-thin samples with a thickness of as low as 0.5 μm.
- Requires controlled sample and knife temperature.
Ultramicrotome:
- Allows the preparation of extremely thin sections.
- Typical thickness: 40-100 nm for transmission electron microscopy.
- Uses diamond knives (preferably) and glass knives.
Vibrating microtome:
- Operates by cutting using a vibrating blade, allowing for less pressure and easier cutting.
- Typically used for difficult biological samples.
- Cut thickness: 30-500 μm for live tissue and 10-500 μm for fixed tissue.
Saw microtome:
- Especially for hard materials such as teeth or bones.
- Has a recessed rotating saw that slices through the sample.
- Minimal cut thickness: approximately 30 μm.
Laser microtome:
- Contact-free slicing.
- No prior preparation of sample required.
- Can be used for very hard materials, such as bones or teeth, as well as some ceramics.
- Thickness: 10-100 μm.