Transmission electron microscope (TEM)

Definition

A transmission electron microscope (TEM) is a powerful imaging tool that uses a beam of electrons to create highly magnified images of ultrathin specimens. It allows for the visualization of fine cellular structures and organelles at the nanometer scale.

5 Must Know Facts For Your Next Test

1. A TEM uses electrons instead of light to achieve much higher resolution.
2. Specimens must be very thin, typically less than 100 nanometers thick, to allow electrons to pass through.
3. Images produced by TEMs are two-dimensional and highly detailed, revealing internal structures of cells.
4. The preparation of specimens for TEM involves processes like fixation, dehydration, embedding in resin, sectioning, and staining with heavy metals.
5. TEMs require vacuum conditions because electrons can be scattered by air molecules.

Review Questions

• What type of radiation does a TEM use to create images?
• Why do specimens need to be ultrathin for observation under a TEM?
• What kind of detail can you expect from images produced by a TEM?

Related terms

Scanning Electron Microscope (SEM): A type of electron microscope that provides three-dimensional images by scanning the surface with a focused beam of electrons.

Ultrathin Sectioning: A specimen preparation technique where samples are sliced into extremely thin sections for electron microscopy.

Staining with Heavy Metals: A technique used in electron microscopy where heavy metals like lead or uranium are used to enhance contrast in the specimen.