Discussion
Why use Cryo-Preservation Techniques to Study the Ultrastructure of Biological Material
Rapid freezing and freeze-substitution are preferable to standard, room-temperature chemical fixation techniques for several reasons. First, rapid-freezing brings biological activity uniformly to a halt within a matter of milliseconds. Chemical fixation, on the other hand, is progressive and takes many minutes or hours to halt cellular processes. Since many cellular events are very rapid (i.e. vesicle budding in the Golgi apparatus) the chemicals cannot stop everything all at once, thus the cell cannot be studied in its truly native state. Second, freeze-substitution allows for the removal of water (dehydration) and infusion of fixatives while the cells is still in a frozen state. This means that the artifact introduced by multiple changes of increasing concentrations of solvents at room temperature is avoided.
Posted on 09/24/08 03:11pm by Jotham Austin