New methods for the histochemical demonstration of catecholamines, tryptamines, histamine and other arylethylamines by acid- and aldehyde-induced fluorescence

The histochemical demonstration of catecholamines, tyramines, tryptamines, and related substances depends upon condensation reactions leading to ring closure, ultimately forming a fluorescentisoquinoline, quinonoid or β-carboline. At present, formaldehyde is widely used for such reactions. In this paper the possibilities of other histochemical reagents are considered, and preliminary results obtained with fixative vapours of some other aldehydes (acetaldehyde, glutaraldehyde) and carboxylic acids (formic and acetic acids) are described.