ultramicrotomy

Ultramicrotomy is a method of preparing sections for TEM observation of biological and polymer materials using an ultramicrotome.
The method enables preparation of an ultrathin section with a thickness of a few 10 nm to 100 nm. A specimen block sent out with a preset feed rate (several tens of nm to 100 nm) is sliced into ultrathin sections by moving the block from top to bottom against the diamond knife. Then, a series of ultrathin sections is prepared (see movies). Each ultrathin section floating on the knife boat is collected onto a grid for TEM observation. It is common to use a section with a thickness of about 70 nm to obtain enough image contrast. Depending on the hardness of a resin for specimen embedding and on the environmental temperature, the sliced sections sometimes do not have the preset thickness. Thus, the final selection of an ultrathin section with a desired thickness for TEM observation is performed by utilizing the interference color of the ultrathin sections floating on the knife boat. If a specimen block is soft and cannot be sectioned at room temperature, thin sections are prepared with a cryo-microtome working under liquid nitrogen temperature.

Ultramicrotome (Leica UC7)

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