Microtomas are sharp instruments for preparing preparations used in microscopy. To meet the high demands of such preparations, microtomas allow extremely fine cups. Modern microtomas allow cuts with a thickness of 0.1 to 100 μm. As a comparative basis: Human hair has a thickness of between 50 and 70 μm. The history of microtomas started with the start of light microscopes. To analyze objects, they had to be thin enough for the light to penetrate them. The first microtomas were at the beginning of single blades (usually razor blades) with which the cuts were done manually. The requirements for increased preparations, it was necessary for microtomas to develop.
The first microtomas, as we know them today, have been developed in 1770. They allow to attach the test and adjust the thickness of the cut with screws. Nowadays, mechanical microtomas are composed of a block, sample holder and technical equipment for advance control. The quality of the preparations depends on the type of advance, the geometry of the blade and the declination (angle between the blade and the direction of the cut). In addition, the result can be influenced by the preparation of the sample (for example by freezing). In addition to mechanical microtomas, laser microtomas are increasingly used, which makes it possible to prepare contactless samples. Here is the operation of some microtomes:
Sliding microtomes
These microtomas are composed of a fixed sample holder and a blade fixed on a blade. To ensure a stable cut, microtoma sliders usually weigh a lot. During the cut, the blade is pressed in the sample. The sliding microtomas allow cuts with a thickness of 1 to 60 μm.
Advantage:
• Due to its design, it causes few failures.
• It allows accurately regulate the pressure of the blade on the fabric.
• Due to the size of the blade, it is possible to discover large head blocks.
• The layout of this blade makes it possible to cut blocks included in the celloidine.
Disadvantages:
• Does not allow the cuts in series, which slows down the process.
• The exposure of the blade can cause accidents
• It is almost impossible to get sections of thickness less than 8 microns.
Rotary microtomes
These microtomas, also called microtomas of Minot, have a fixed blade and a mobile sample holder. The name of the rotation microtome is given because the sample holder is activated by a steering wheel. The rotational movement of the steering wheel becomes a rectilinear movement. Normally, the sample holder of these microtomas moves down. Prepared samples accumulate on the blade. The advantage of these microtomas is that the high mass of the inertia flywheel corresponds to the different hard tests of the same test, which makes it possible to obtain a uniform cut. The rotating microtomas make it possible to prepare samples between 1 and 60 μm.
Advantage:
• With more weight, more precision, this makes it possible to obtain very fine serrated sections.
• The advance mechanism is more precise.
Disadvantages:
• The high price due to the complexity of the advance mechanism, which also makes repairs more difficult and expensive.
• The impossibility of cutting with her tissues included in the celloidin, gelatin and propylene glycol.
Freezing microtomes
Freezing microtomas are a subcategory of rotating microtomas. The test takes place in a freezer which is cooled, for example, to nitrogen. The low temperature increases the hardness of the test.
Ultramicrotomas
With ultramicrotomas, samples are prepared for transmission electron microscopes. As the preparations must be extremely thin, these microtomas have special blades and a very fine advance, often driven by thermal dilatation. The use of these microtomas allows a thickness of 10 to 500 nm.
Laser microtomes
Laser microtomas use a special laser for cutting. They are distinguished by their high concentration and very short duration. This makes it possible to cut the tests very finely without causing thermal damage to the material to be tested. These microtomas make it possible to prepare samples of a thickness of between 10 and 100 μm. Kalstein offers sophisticated microtomes that will allow you to offer the best analysis as they have the best technology. That’s why we invite you to take a look at our microtomes available in HERE