Staining of granulocytic cells by Chlorazol black E

Using the trisazo dye Chlorazol black E, granules in neutrophilic granulocytes stained pale orange, gray and black. In promyelocytes, granules were mainly orange, whereas in myelocytes and metamyelocytes, mixtures of orange and black granules were seen. In neutrophils, a few orange granules were seen, and most of the granules stained gray and black. In eosinophils and basophils, granules stained orange. In monocytes, a few black and gray staining granules were seen. In lymphocytes, as well as other marrow cells like erythroblasts and megakaryocytes, granules were not visualized. Chlorazol black E may be a useful addition to the cytochemistry of blood cells, particularly in distinguishing cells of granulocytic origin from other cell types.