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The components of the hematoxylin and eosin (H & E) stain (i.e. hemalum and eosin Y), their contributions to the typical staining pattern, and the reasons why the H & E stains are the preferred oversight stains for routine diagnostic histopathology are discussed. The essential diagnostic significance of effective nuclear staining by hemalum, providing information on nuclear morphology and texture, is emphasized; as is the ironic advantage for routine diagnostic histopathology of the limited range of colors provided by H & E staining, that allows recognition of significant features under low microscopic magnifications. Standardization of hemalum is considered, along with probable reasons why users show resistance to such a concept. Counterstaining with anionic (acid) dyes is discussed, as is the important phenomenon of contrast. The particular advantages and disadvantages of eosin Y and phloxin B as counterstains to hemalum are outlined. The concept of an "ideal routine histological stain" is considered, and H & E is compared to such an ideal case. Finally, deficiencies of H & E staining are discussed, and a program to develop an improved oversight stain is introduced.

A new and technically simple Romanowsky-Giemsa (RG) stain is proposed as a standardized technique for use in histology. An RG stock solution (pure azure B 7.5 g/l, eosin Y as eosinic acid 1.2 g/l in dimethylsulfoxide) is diluted to form the working solution with HEPES-buffer, pH 6. Staining time is 30-90 min after formol-calcium solution (or 2-4 hr after formaldehyde-organic acid mixtures). The resulting overstained sections are to be differentiated. A tannic acid-acetic acid combination in an isopropanol-water mixture was found to give optimum results within 100 sec. Subsequent dehydration is in isopropanol only. The staining pattern obtained is polychrome. The distribution of colors in detail is influenced by the modes of pre- and posttreatment. Of practical interest is the development of green and greenish blue colors on collagen fibrils which contrast strongly against the pink of sarcoplasm. For this and other reasons, this RG stain version seems suitable to replace the trichrome Gomori-type trichrome stains under appropriate processing conditions.

Eine Methode zur Anfarbung von Blut- und Knochenmarkausstrichen wird beschrieben, dadurch gekennzeichnet, das nur mit zwei Farbstoffen, reinem Azur B und Eosin, gefarbt wird. Die Ergebnisse sind denen gleichwertig, die mit der May-Grunwald-Giemsa-Farbung (MGG) erreicht werden. Die Azur B-Eosin-Farbung last sich jedoch standardisieren, sie ist auch einfacher durchzufuhren. Beziehungen zwischen Azur B-Eosin- und May-Grunwald-Giemsa-Farbung werden kurz besprochen.

Summary. An azure B-eosin Y stain is described which is intended to fulfil the requirements of a standard Romanowsky-Giemsa stain. It consists of pure azure B and eosin Y only and gives strictly reproducible staining results.

Two stains long used in exfoliative cytology, the hematoxylin-eosin Y and Papanicolaou stains, have not been standardized even today. Some dozens of hematoxylin and eosin and Papanicolaou staining recipes have been recommended in the literature. Consequently, the staining pattern of hematoxylin and eosin, and Papanicolaou stained cytological material varies from laboratory to laboratory. To a certain degree this is due to batch-to-batch variations of commercial samples of the natural dye hematoxylin (C.I. 75290). The present paper describes a simple, standardized and reproducible procedure using thionin bromide to replace hematoxylin in the hematoxylin and eosin stain.

A method is described for the purification of the dye azure B in quantities sufficient for biological staining experiments on a larger scale. The method is based on the use of column chromatography. Two columns are employed. In column A with silica gel as adsorbent the azure B fraction is isolated from a suitable substrate ('technical' azure B gained by a modification of Bernthsen's synthesis of methylene blue, or polychrome methylene blue) using an acetate-formate mixture as eluent. In column B, on an Amberlite polymeric adsorbent (XAD-2) the acetate-formate anions are exchanged in chloride. Regeneration of both columns is possible: KMnO4, Na2S2O4 and water are run through column A; 5% NaOH, methanol and water through column B. Purification of azure B on economic terms is thus attained. The opinion is expressed that this method is also applicable to the purification of other cationic dyes.

The Giemsa stain is one of the most widely used staining techniques in cytology, especially in hematology. A standardized Romanowsky-Giemsa staining procedure using pure cationic azure B (C.I. 52010) and anionic eosin (C.I. 45380) has been described by Wittekind et al (1982). A revised standard Giemsa staining procedure was recently published (Wittekind and Kretschmer 1987). Usually the Romanowsky-Giemsa stain is applied to air dried and methanol fixed cytological material, e.g. blood smears and bone marrow films (ICSH 1984).