electrical microtome Microm HM 200.

A microtome is a mechanical instrument used to cut biological specimens into transparent thin sections for microscopic examination. A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are Microtomes use steel, glass, or diamond blades depending upon the specimen being sliced and the desired thickness of the sections being cut. Steel blades are used to prepare sections of animal or plant tissues for light microscopy histology. Histology (from the Greek = 'tissue' is the study of the microscopic anatomy of cells and tissues of Plants and Glass knives are used to slice sections for light microscopy and to slice very thin sections for electron microscopy. Industrial grade diamond knives are used to slice hard materials such as bone, teeth and plant matter for both light microscopy and for electron microscopy. Gem quality diamond knives are used for slicing thin sections for electron microscopy.

Applications

The most common applications of microtomes are:

• Traditional histological technique: tissues are hardened by replacing water with paraffin. In chemistry paraffin is the common name for the Alkane Hydrocarbons with the general formula C n H2 n +2 The tissue is then cut in the microtome at thicknesses varying from 2 to 25 µm (micrometers) thick. From there the tissue can be mounted on a microscope slide, stained, and examined using a light microscope. See histology for more details. Histology (from the Greek = 'tissue' is the study of the microscopic anatomy of cells and tissues of Plants and
• Cryosection: water-rich tissues are hardened by freezing and cut frozen; sections are stained and examined with a light microscope. This technique is much faster than traditional histology (5 minutes vs 16 hours) and is used in conjunction with medical procedures to achieve a quick diagnosis. Cryosections can also be used in immunohistochemistry as freezing tissue stops degradation of tissue faster than using a fixative and does not alter or mask its chemical composition as much. Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibodies binding specifically
• Electron microscopy: after embedding tissues in epoxy resin, a microtome equipped with a glass or gem grade diamond knife is used to cut very thin sections (typically 60 to 100 nanometers). Sections are stained and examined with a transmission electron microscope. This instrument is often called an ultramicrotome. The ultramicrotome is also used with its glass knife or an industrial grade diamond knife to cut survey sections prior to thin sectioning. These survey sections are generally 0. 5 to 1 micrometer thick and are mounted on a glass slide and stained to locate areas of interest under a light microscope prior to thin sectioning for the TEM. Thin sectioning for the TEM is often done with a gem quality diamond knife.
• Botanical microtomy: hard materials like wood, bone and leather require a sledge microtome. These microtomes have heavier blades and cannot cut as thin as a regular microtome.
• Spectroscopy, especially FTIR or infra-red spectroscopy, where thin polymer sections are needed in order that the infra-red beam will penetrate the sample under examination. Infrared spectroscopy (IR spectroscopy is the subset of Spectroscopy that deals with the Infrared region of the Electromagnetic spectrum. It is normal to cut samples to between 20 and 100 micrometres in thickness. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre For more detailed analysis of much smaller areas in a thin section, FTIR microscopy can be used for sample inspection. Microscopy is the technical field of using microscopes to view samples or objects

Microtome blades are extremely sharp, and should be handled with great care. Safety precautions should be taken in order to avoid any contact with the cutting edge of the blade.

A recent development is the laser microtome, which cuts with a femtosecond laser instead of a mechanical knife. The laser microtome is an instrument used for non-contact sectioning of biological tissues or materials This method is contact-free and does not require sample preparation techniques. The laser microtome has the ability to slice almost every tissue in its native state. Depending on the material being processed, slice thicknesses of 10 to 100 µm are feasible.

See also

• Histology
• Microscope