Critical Point Drying of Biological Specimens for Scanning Electron Microscopy

Although several methods can be used to dry specimens for examination with the scanning electron microscope (SEM), critical point drying (CPD) is by far the most widely used. The technique was first introduced by Anderson (1 ) to preserve three-dimensional structure of biological specimens for transmission electron microscopy. Later, it was reintroduced (2 ) as a method of obtaining dry specimens for SEM examination.