Friday, January 26, 2007

The transmission electron microscope (though not the same as Transmitted Light Microscope) is the first type of electron microscope to be developed and is patterned exactly like the light microscope, but it uses electrons instead of transmitted/reflected light. Electron microscopes can make it possible to view objects as small as the diameter of an atom. Indeed, most electron microscopes used to study biological material can magnify objects up to 1 million times. Though it does not make atoms visible, this method allows researchers to distinguish individual molecules of biological importance. There is a drawback, however, and it's in the sample preparation. Because living specimens must be dehydrated, frozen, or fixated using a negative staining material, this process makes it difficult to see the ever-changing movements that characterize a living cell.