Computer-operated microspectrofluorimetry to identify formaldehyde-induced fluorophores of biogenic monoamines and precursor substances in models and tissue sections.

By means of a histochemical reaction using formaldehyde vapour (Falck and Owman 1965), biogenic monoamines and precursor substances, i.e., L-DOPA, dopamine, noradrenaline, adrenaline, 5-hydroxytryptophan and 5-hydroxytryptamine, may be converted into fluorophores with specific spectral characteristics, i.e., the emission spectrum, excitation spectrum and fading curve. The registration and correction of the spectral properties and changes induced by acidification with hydrochloric acid vapour or treatment with ammonia vapour, of these formaldehyde-induced fluorophores, are performed by an automated microspectrofluorimeter, developed by modification of a Leitz MPV 2 system. This work deals with the instrumental configuration and certain methodological features in order to identify the fluorogenic biogenic monoamines and precursor substances in models and tissue sections. Registrations of excitation peak values, for the first time extended to a wavelength range from 240-460 nm, are discussed, which enable the calculation of peak ratio values 410/260, 380/320, 320/260 or 385/315, suitable as identification parameters for formaldehyde-induced fluorophores of biogenic monoamines and precursor amino acids.