Wright Stain

WRIGHT STAIN (Wright) is used for staining blood smears. Preparation method: A 1% solution of basic (medical) methylene blue in a 7₂% aqueous solution of sodium bicarbonate is poured into a vessel so that the height of the liquid layer does not exceed 6 cm, and heated in a Koch apparatus at 100° for 1 hour (from the moment of steam formation). The liquid is then cooled and filtered. The cooled filtrate in a thin layer under artificial light should have a purplish-red tint. To 100 cm³ of filtrate, 500 cm³ of 0.1% aqueous solution of eosin (yellowish, water-soluble) is added. When both liquids are mixed, a large precipitate forms immediately; the latter is filtered and dried. The dye obtained in this way is dissolved in a mortar in methyl alcohol in the ratio of 0.1 to 60.0. Ready-made dry dye is commercially available (from Coleman and Bell, U.S.A.).-Staining method: Several drops of the dye are poured onto a dry, unfixed blood smear; after 1 minute, an equal number of drops of distilled water are added. After 2-3 min., the preparation is washed in water (for about ¹/₂ min.) until it takes on a pinkish tint in a thin layer. Result of staining: Due to the presence of azure, a cherry-red color of the nuclei is obtained, and azurophilic granulation is revealed in both leukocytes and lymphocytes, with the granulation being especially clearly pronounced in monocytes. The Wright method, while somewhat inferior to the Giemsa and Nocht methods in terms of azure staining, has all the advantages of the May-Grünwald and Jenner method (see Blood-morphological composition of blood and methodology of its research) in terms of the clarity of staining of neutrophil, eosinophil, and especially basophil granulation.