Cytofluorimetric scanning: a tool for studying axonal transport in monoaminergic neurons

A new technique is described which makes it possible to measure several substances and parameters related to axonal transport in peripheral nerves. The technique is based on histofluorescent techniques and measures accumulated amounts of fluorescent substances, e.g. proximal to a crush or local cooling of the nerve. Sections from nerves, treated according to the FIF method for visualization of catecholamines or for immunofluorescence, are placed in a cytofluorimeter (Leitz MPV 2). The nerve sections are passed under a measuring slit by a motor-driven cross-table and the fluorescence intensity is continuously registered via a recorder with integrator which gives a graphical "nerve-accumulation profile." Comparisons between accumulation curves obtained with the cytofluorimetric scanning technique and biochemically determined accumulation curves of noradrenaline, dopamine-beta-hydroxylase and tyrosine-hydroxylase in the sciatic nerve following crush operations, demonstrated a striking similarity. With this technique it is possible to semiquantify the accumulated amount of a fluorescent substance, study morphology, perform morphometry and photographical documentation in the same section. This scanning technique may prove useful, since the accumulation and distribution of several substances in consecutive sections, along the length of a nerve, can be demonstrated graphically using superimposed curves.