The effects of preparative procedures for scanning electron microscopy on the size of isolated lymphocytes.

The diameter of lymphocytes, isolated from a sample of peripheral blood by Ficoll-Hypaque sedimentation, was determined after eight different steps in the preparative procedure for scanning electron microscopy (SEM). There was a 43% total reduction in mean cellular diameter of the lymphocytes studied, the diameter dropping from 8.4 mum prior to fixation, to a final diameter of 4.8 mum in the cells examined under the scanning electron microscope. The bulk of this shrinkage occurred during critical-point drying. In view of this finding, caution should be exercised in describing detailed cell surface morphology by SEM when similar preparative procedures are employed.