A simple and reproducible staining procedure to assess characteristic effects of some fixatives.

The standardized Romanowsky-Giemsa-Stain, adapted for use in histology, is recommended as a suitable technique to assess effects of fixatives. The stain consists of two dyes only--Azure B and Eosin Y--but gives a polychrome and reproducible staining pattern. Most important is the colour purple which results from Azure B-Eosin Y molecular interaction. A collection of fixative effects on the RG-staining pattern is given. They are not easily revealed by other equally simple histochemical techniques. Of special interest is the fixative-dependent development of the colour purple on various biological substrates. For instance, both formaldehyde and acrolein allow the generation of this colour on collagen fibers but only after formaldehyde, hardly after acrolein, will the full colour purple appear on chromatin. A list of substrates, RNA among them, is presented which will not stain purple after any of the fixatives employed. The results are briefly discussed.