[Visualization of specific leukocyte granules using morin and other fluorochromes]

The visualization of the specific granulation of leukocytes is useful in hematology to identify de cell type in leukemic diseases. The authors employed the acidic fluorochrome morin after testing its high affinity for the fluorescent reaction with morin in human and chicken peripheral blood smears, and in streak smears from rabbit spleen. The best results were obtained with a solution prepared either with 0.10 mg morin per ml of 50 per 100 ethanol, or with a saturated solution of morin in distilled water diluted to one fourth in 25 per 100 ethanol. When observed under blue-violet excited light (436 nm) the acidophilic granules of leukocytes produce a bright yellow fluorescence, while the cell nuclei show a faint greenish fluorescence. As for the mechanism of the reaction, it consists possibly in an interaction between morin and the basic components of the granules. Other acidic fluorochromes, as primulin and hematoxylin, produce similar fluorescent reactions with the acidophilic granules.