ABSTRACT
Methylene blue and the azures are basic dyes, and structures that combine with them are basophilic. The observed color reactions, however, depend upon the nature of the fixative used and on the pH of the staining solution. Thus when Giemsa stain is applied it is necessary to know these conditions in order to interpret the color reactions correctly. When a structure stained with Giemsa is reported as basophilic, it is understood that it has stained blue under the particular, and usually unspecified, conditions of the experiment; but with another stain the structure may be shown to be acidophilic and stain red with eosin. In stating the reported staining reactions of inclusions we have usually used the terms employed by the authors of the papers, but these should be interpreted with caution. In some instances the same kind of inclusion has been described as basophilic or eosinophilic by different authors. The paper by Kato et al. (Reference 107 in Chapter 5) considerably clarified the position by showing that inclusions which were blue when fixed with methanol and stained with Giemsa, were bright red when fixed with Bouin's fluid and stained with hematoxylin-eosin. We have demonstrated that a similar situation exists with reovirus inclusions (Figures 23 and 24), * and also with rotavirus inclusions (Figures 26 and 29).
