ChEBI: Thionine is an organic chloride salt composed of 3,7-diaminophenothiazin-5-ium and chloride ions in a 1:1 ratio. A strongly metachromatic dye, useful for the staining of acid mucopolysaccharides. It is also a common nuclear stain and can be used for the demonstration of Nissl substance in nerve cells of the CNS. It has a role as a histological dye and a fluorochrome. It contains a thionine cation.
