High‐voltage electron microscopy of inorganic particles in intact blood cells

SUMMARY Preliminary results obtained by examining intact fixed human red and white blood cells containing inorganic particles under the high‐voltage transmission electron microscope are described. Iron filings and ferritin ingested in vitro by granulocytes were observed as were inorganic particles in red cells from a case of lead poisoning. The nature of the particles in red cells is discussed. A faint intracellular network was seen in normal red cells and in cells from a case of lead poisoning. It was found possible to focus the electron microscope at different planes within the cell. The optimum accelerating voltage for red cells appeared to be around 750 kV, whereas a clear image of granulocytes was obtained at voltages between 750 and 1000 kV. The first results indicate that it is possible to examine intact blood cells under the high‐voltage electron microscope. Further work is in progress to determine if more information can be acquired by this technique.