Introduction

The traditional wright’s stain, an alcoholic solution of methylene blue and eosin Y, dates from the early 1890’s. Since then there have been many modifications, most involving partial oxidative demethylation of the methylene blue to improve polychroming. Modern day samples of the dye usually contain mixtures of methylene blue, azure A, and thionin ( the mixture is often called “polychromed methylene blue”) compounded with eosin Y. Med Chem’s Wright’s Dip Stat has the azures and the eosin Y in separate solutions which improves staining control and reproducibility as well as speed. The total staining time is about thirty seconds.

Reagents

Specimen Collection

Use capillary blood or freshly drawn venous blood that has not been treated with anticoagulants. Hemolysis will render the sample unsatisfactory.

Procedure

1. Fix Blood films in absolute methyl alcohol for 30 seconds.
2. Transfer the fixed smear to the eosinate stain (Wright’s Dip Stat #2) for six seconds.
3. Rinse the slide in deionized or distilled water.
4. Immerse the rinsed smear in polychrome stain (Wright’s Dip Stat #3) for twenty seconds.
5. Rinse with distilled or deionized water and air dry.

* Staining times vary with the thickness of the slide. Exact staining time should be established by each laboratory.

Sources of Error

1. Staining time will vary.
2. Blood smears should be thin.
3. The rinsing solution should be distilled or deionized water. Tap water is unacceptable because the chlorine will bleach the stain.
4. White cells will degrade in stored smears. Smears should be fixed and stained within about one hour of production.