Ultramicrotomy

Ultramicrotomy is a method for cutting specimens into extremely thin slices, called ultra-thin sections, that can be studied and documented at different magnifications in a transmission electron microscope (TEM).

With Epon or Vestopal as embedding medium the ridges and valleys usually do not exceed 0.5 μm in height, i.e., 5–10 times the thickness of ordinary sections (1).

Specimens may be from biological matter, like animal or plant tissue, or from inorganic material such as rock, metal, magnetic tape, plastic, film, etc.

An area is chosen to be sectioned for TEM and the block face is re-trimmed to a size no larger than 0.7 mm on a side.

In 1952 Humberto Fernandez Morán introduced cryo ultramicrotomy, which is a similar technique but done at freezing temperatures between −20 and −150°C.