Scanning electron microscopy of human leukocytes.

Extensive application of scanning electron microscopy (SEM) to the study of normal as well as of pathological human leukocytes has been pursued over the last ten years. Initial efforts to recognize, under the SEM, the two main subpopulations of circulating lymphocytes have met with limited success. However, a critical evaluation of the cell preparatory methods has emerged from the initial difficulties. Highly reproducible SEM images of leukocytes can now be obtained, and their significance correlated with immunological and/or cytochemical parameters. This resulted from the development of highly specific techniques for the immuno-labeling of cell surfaces, and from the development of SEM cytochemistry in the backscattered electron imaging (BEI) mode. A basic procedure for the SEI imaging of separated peripheral blood leukocytes (PBL's) is critically presented with the hope of facilitating significant future applications of SEM in diagnostic clinical hematology.