Night blue, or nacht blau, has been used in Europe for a decade to stain acid-fast organisms. Its introduction by Hallberg1 as a useful stain for Mycobacterium tuberculosis and Mycobacterium leprae unfortunately did not create any further interest in its potentialities. In a series of investigations concerning low-temperature mycobacteria in hairless mice, the specific keratinophilia of night blue was noted. In pursuing this matter, I2,3 found that the mast cells of the rat, mouse, and hamster stained selectively with night blue. It is the purpose of this paper to organize some of the knowledge about the technique of staining with night blue, so it can be used in work with the skin.
The staining technique depends on the alcohol differentiation of the dye-protein complex produced by incubation for one hour at 60 C. Most tissues quickly lose their affinity for night blue in alcohol; a few do not
WINKELMANN RK. Use of the Night Blue Stain in Dermatology. AMA Arch Derm. 1960;81(3):417–421. doi:10.1001/archderm.1960.03730030075012
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