THE HISTOCHEMICAL FLUORESCENCE METHOD FOR THE DEMONSTRATION OF CATECHOLAMINES THEORY, PRACTICE AND APPLICATION

The formaldehyde fluorescence technique is a highly sensitive and specific method for the demonstration of catecholamines (CA) at the cellular level. It permits the demonstration of as little as about 5 x l0–4 pg noradrenaline, present in a single varicosity. The method can also be used for quantitative microfluorimetric studies on the CA stores at the cellular level, although a concentration-dependent quenching of the fluorescence in locations where the CA concentration is very high may impose some limitations. The sensitivity of the technique has been increased by using sections of unembedded tissue from unfixed or formalin-fixed tissue (Hökfelt and Ljungdahl). A glyoxylic acid technique, recently introduced by Axelsson and his co-workers, may prove to be an additional reliable alternative method for the demonstration of CA. Examples of neurobiologic problems that could be approached by using the formaldehyde fluorescence technique are briefly reviewed.