Microtome

Microtome - the device for making thin histological sections of tissues of animals and plants. Microtome consists of rolling table, which enshrined the object, and microtome knife. In some microtomes table with object each time rises to the specified height equal to the thickness of a cut of a knife blade moves in a horizontal plane through the fabric. Sometimes knife strengthened still, and moves vertically table with object each time navigasi at the knife.

sliding microtome
Fig. 1. Sliding microtome: 1 - micrometer screw; 2 - rocker mechanism; 3 screws that secure the core Foundation of objectutilities; 4 - pin base of objectutilities.

Sledge microtomes (Fig. 1) used for tissue sections, pre prisoners in waxes or celloidin. Main parts sliding microtome the bed, the mechanism of micropolicy, lifting mechanism, the object sled with clip for fabrics, caliper with niederheim. For making sections unfixed tissue, and also in cases when it is necessary to study the object in a short period of time, use the freezing microtomes (Fig.2)with freezing table, on which strengthens the investigated object. Table flexible hose connected to a metal container in which there is a liquid carbon dioxide. For freezing of tissue blocks used as thermoelectric cooling table (TOS-1) with selenium rectifier: electrical appliance, building of which has an active cooling surface and fittings for leading water and electric current.

freezing microtome Fig. 2. Freezing microtome.

Microtome should be kept clean and regularly lubricated friction surfaces (bed guides, threaded part of microvista, guide and rubbing the surface of lifting mechanism) vaseline oil. For making ultra-thin slices, suitable for studies under an electronic microscope, used ultramicrotomy.
The greatest distribution recently received ultramicrotomy, consisting of a steel rod, one end of which strengthened the object, wedged in the holder, and the other is connected with the base of the instrument tape spring. Rod moves freely up and down is made by a motor, shaft which is associated with a terminal. When lowering rod object passes by knife (glass, diamond and cut it appears on the surface of the liquid baths attached to the knife. The accuracy of the return of the knife to its original position is ±10+.
Cm. also Histological techniques.

Microtome (from the Greek. mikros - small and tome - cutting, clipping) - equipment for manufacturing of histological sections. Among the current microtomes most common sledge, radial, or rotational (Fig. 1-4). The main parts of the microtome are: a massive base (building), feeding mechanism with a micrometer screw, the holder of an object (or a table) and the holder of microtome knifes.
In toboggan-microtomes (Fig. 3 and 4) in the upper part of the base are ground plane on which slides massive movable support. In the fixed caliper knife holder, provided with a device which allows you to set the knife or transversely to the direction of its motion (for frozen and paraffin sections), or COSO (for celloidin slices), and change the pitch angle of the knife. When you pull the knife back to failure included semi-automatic feed mechanism that raises the holder of the object (table) for a specified number of microns.
The holder of the object supplied screws, allowing to secure the unit in position relative to the plane of motion of a knife. Micrometric screw feeder in most modern models is installed in the inclined plane, but are produced and model with vertical screw.
Rarely in the toboggan microtomes knife set still, and on the polished planes moving object with a holder.
In the radial microtomes (Fig. 1) the holder of a knife is fixed at one end, and the adjustment can be measured only in the angle of the knife. Feed mechanism with vertical installation micrometer screw is included, as in the toboggan microtomes, you remove the handle from yourself. M. these two types usually have a device that allows you to replace the holder of the object to be embedded in paraffin or celloidin pieces special table to get frozen liquid carbon dioxide cuts. Radial M not always allow to receive thin slices of paraffin and especially in celloidin material. Often these systems are used to obtain frozen sections; often referred to as "freezing microtome".
Rotary microtome (Fig. 2) has a fixed blade, fixed horizontal blade up. The holder of an object is moved up and down by turning the hand wheel or motor. A special mechanism nominates the holder of the object each time it is picked up by a specified number of microns. The sections one by one slip of the knife on the special belt, moving synchronously with the holder. This type M is especially convenient to obtain the serial sections with paraffin material.
These types Meters allow to be sliced no thinner than 1 micron (usually 5-15 MK). For more thin slices, for example for working with electronic microscope, are ultratome and ultramicrotomy (see).
Cm. also Histological techniques.

Fig. 1. Radial microtome with a table for freezing of the object.
Fig. 2. Rotary microtome with ribbon for acceptance serial sections.
Fig. 3. Sliding microtome (General view)
Fig. 4. The scheme of arrangement of large sliding microtome with an inclined plane: a - side view; b - top view; 1 - frame; 2 - washer with divisions for manual filing of the facility; 3 - runners for a slip of objectutilities; 4 - spindle micrometer; 5 - flow drip baths; 6 - drip bath; 7 - a bar for semi-automatic submission of the object; 8 - the holder of the object; 9 - knife holder; 10 - knife; 11 - the knife block; 12 - runners for a sliding block.