Would it be useful if you could examine a wet, perhaps even a living, specimen in the scanning electron microscope? Of course we think that this would be impossible, given the vacuum the specimen would be subjected to in the microscope. However, in the realm of materials research, the Environmental Scanning Electron Microscope (ESEM) is being developed. Apparently this instrument has not been fully appreciated and utilized by biologists.

As reviewed by Athene Donald, a pioneer in developing the ESEM, this instrument has been commercially available for a decade. It is still evolving as a useful tool in looking at materials such as cement, natural fibers, and aqueous dispersions. Applications of the ESEM. to biological Studies are extremely limited. However, studies on biological samples, even living cells, are possible (although not without problems and limitations).