Advantages of visualization of organelle structure by high resolution scanning electron microscopy

Abstract

AbstractExamination of subcellular structures in detail and in three dimensions (3D) by scanning electron microscopy (SEM) is now possible on a routine basis due to improvements in design of the modern scanning electron microscope and new methods of specimen preparation involving chemical removal of the cytosol and the cytoskeleton. Cells which have been fixed, frozen, cleaved, thawed, and subjected to cytosol removal exhibit constituents such as nuclear chromatin, cisternae of endoplasmic reticulum, mitochondria, and the Golgi complex in bold relief. This permits examination by SEM in 3D of these structures from several aspects at a resolution close to that of conventional transmission electron microscopy (TEM). As a result, minute changes in the 3D structure of subcellular components can now be easily and conveniently examined from many specimens and anatomical sites, in development, in a variety of physiological processes, and in disease. The SEM method offers many advantages over the various TEM techniques now used for similar purposes, since much larger areas of the specimen can be surveyed by SEM in a given time, sectioning is not required and minute 3D changes in nuclear and organelle structure can be identified and analyzed more easily. The advantages are such that a host of biological questions can now be answered by SEM which, so far, have resisted solution using only TEM techniques. In addition, a new field of pathological diagnosis using SEM may develop, using the advantages offered by the technique in exploring the cell's interior as well as cellular tissue organization.