Freeze etching proved to be an optimal method for the depiction of membrane surfaces. The resolution is high enough to recognize single macromolecules or macromolecular complexes, especially, if they are arranged in the membrane in regular patterns as two-dimensional crystals . The use of glutaraldehyde as a conserving agent allowed the depiction of tube-shaped structures, the microtubuli . Among the peculiarities of a plant cell is the cell wall , whose layered structure could be confirmed by electron microscopical analysis.
Layers occur also in collenchyma, stone or corked cells.
The use of highly specific markers or probes to localize certain molecules or classes of molecules is another important technique. We will discuss this problem later. It represents a bridge to the molecular level. To stress this further, it is also spoken of the molecular architecture of a cell. Independent of the mentioned methods are the attempts to analyze electron microscopic pictures with the aim to reveal the three-dimensional shape of intracellular structures.