ABSTRACT
Transmission electron microscopy (TEM) has made great strides in the last three decades in the elucidation of cell wall structure and complexity. A number of techniques have been developed in TEM cytochemistry, essentially adapted from light microscopic cytochemistry. For TEM studies, the use of fresh tissue will not normally provide adequate ultrastructural preservation and so some form of chemical fixation is necessary. Use of fixatives is the most widely employed method in TEM tissue preparation. Size of the tissue is a critical factor in TEM fixation. Fixation by immersion of tissue in the fixative is limited to 2 to 3 cell layers from the surface. So, the smaller the specimens, the better and more uniform the fixation. Selection of size of tissue also depends on the fixatives used, as the latter differ in their penetration rate. Immersion of tissue into the fixative usually produces non-uniform fixation.
