Electron Microscopy (SEM)
Scanning electron microscopy can magnify images to
an extent that is impossible with light microscopes. There is also
a greater range of magnifications that one can utilize (see below).
Since the finer details of a frustule can be visualized by using
SEM, the taxonomy of diatoms has drastically changed in recent years.
Check out the Collection & Study section
to see more about microscopy!
The following scanning electron micrographs were taken
using cultures of Pseudo-nitzschia australis and Pseudo-nitzschia
multiseries. Bleach was added to the samples in order to break
open the frustules. Before visualization, the samples were washed,
centrifuged (pellet was extracted), and dried onto a carbon-covered
When compared to the photos taken using light microscopy,
it is easy to see the superior magnification and clarity afforded
by the scanning electron microscope. However, it is still extremely
difficult to observe the differences in the two species of Pseudo-nitzschia.
In reality, the differences between the species of this genus are
minute and are usually given in terms of measurement differences
(of the apical axis, transapical axis, presence of central nodule,
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copyright Jennifer Shin 1999.