Introduction and Methods

Abstract

In recent years the scanning electron microscope (SEM) has been used to study the surface morphology of a variety of mammalian cells. This microscope has a great depth of focus, provides a three-dimensional view of cell surface topography and enables examination of a large number of cells. Thus, SEM provides an overall impression of the surface features of a given population of cells and at the same time details of individual cell surfaces can be obtained. An added advantage of this mode of microscopy is that cells can be prepared relatively quickly for examination in the SEM and results can be obtained within a day if necessary. Much, however, depends on the method of cell preparation and in particular, the modes of fixation and drying employed in the processing of cells for SEM. Earlier studies on leukocytes by a number of workers [9, 15, 16, 34, 54] employing air-drying techniques, did not provide optimal details of surface morphology. Air-drying causes cell distortion and shrinkage with collapse of surface microprojections [10, 82], making it difficult to record details of the surface morphology of the different cell types and to attempt to characterize them on the basis of their structure.