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In this article we will discuss about the types and advantages of using microtome.
Types of Microtomes:
The inherent defects of handmade sections can be eliminated by using a microtome.
Three types of microtomes are available:
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Rotary,
Rocking and
Sliding Microtomes (Fig. 3.1).
A Rotary microtome is worked by rotating a wheel fitted with a handle.
The razor is placed in front of the microtome in a razor- holder which is movable. The material, embedded in a paraffin block, is fixed on the block-holder which can be fixed to an adjustable socket. There is a scale indicating the thickness of the section in microns. The thickness is adjusted by moving a screw.
The block-holding socket can be moved forward or backward by rotating a handle placed at the back of the microtome. Nowadays, rotary microtomes are commonly used. A Rocking microtome has the same working principle. Sections are cut by moving a horizontal handle forward and backward. A Sliding microtome can be used for cutting sections of fresh materials, not embedded in paraffin.
Advantages of Using Microtome:
In free-hand sections, the thickness of the section cannot be regulated, it may be thick or thin, as also oblique. Moreover, the entire material cannot be obtained in sections, as the defective sections have to be thrown away.
When a microtome is used for section-cutting, the sections are of uniform thickness. They can be obtained at any desired thickness (10 or 15 or 20 n etc.). Sections are not oblique. The entire tissue can be retained in sections — this is particularly necessary for studying the development of a plant organ. However, microtome sectioning is a long-drawn and laborious process.