The freehand sectioning of fresh or fixed material using a sharp razor was the earliest form of microtomy. Today, microtome are instruments designed to accurately cut equally thin sections of various materials even those tiny one’s only visible using microscopes. For light microscope, where magnifications can reach up to 1,800x, the thickness of a section can vary between 1 and 10 microns (thin sections). While for electron microscope, where magnifications of several hundred thousands are possible, the thickness of a section is usually of the order of 10 nanometres (ultra-thin sections). Microtomes are made up of three main parts. The base as the main body; the knife and knife holder that perform the slicing and lastly, the material or tissue holder, in order to keep the specimen in place while cutting. Microtomy styles vary depending on the functions and usage required. Amongst it is the Rotary Microtome.

This machine was designed to simply cut semi-thin to thin sections of specimens visible only through the help of light microscope. Rotary microtome are machines that range from lightweight, motor driven instruments used with a slow continuous speed and retracting advance movement to section hard material embedded in synthetic resin suitably for cutting paraffin wax embedded material in continuous ribbon to heavy duty. It is called rotary because it operates based upon the rotary action of a hand wheel activating the advancement of a block towards a tightly held knife. To cut flat sections the knife works in relation to the block that moves up and down in a vertical plane. In cutting frozen sections, rotary microtome can also be found in most cryostats. Rotary microtome section thickness settings range from 0.5µm to 60µm on most machines. While normally cut within the range 3 to 5µm whilst resin sections are between 0.5 to 1µm are for sections of paraffin wax embedded tissues. Rotary microtomes are especially suited to cutting sections using disposable steel knives. Steel microtome knives are manufactured from high quality carbon or tool grade steel which is heated to harden the edge. Steel should be free from impurities, contain anti-corrosives and be rust-resistant. The best knives are those that are fully hardened and can be can be easily loosen from the cutting edge once remove for repeated re-sharpening. These knives consistently produce high quality sections virtually free from compression. Recently, refined thickened razor blades have replaced conventional microtome knives only that they are disposables. Disposable blades need to be held rigid in a special holder to prevent vibration during the cutting stroke. Once attached in a specially adapted knife holder the blades consistently produce high quality sections. All these disposable blades are manufactured from high quality stainless steel although their thicknesses are of different grades. The edge of these blades can be coated with platinum6 or chromium7 to enhance strength and prolong cutting life. Teflon coated blades are particularly suitable for use in cryostats as these offer reduced cutting resistance and minimal friction. The smaller and thinner the blade helps cryostat chamber reach temperature more rapidly than a conventional knife, thus minimizing time delay.