Identification of mast cells in the scanning electron microscope by means of x-ray spectrometry.

In mixed populations of rat peritoneal fluid cells, the mast cells can be differentiated from other cell types in the scanning electron microscope by virtue of the X-ray emission referable to their sulfur content. Both stationary probe and X-ray mapping are feasible; the amount of sulfur eliciting a signal is estimated to be about 8 x 10(-18) g.