Aqueous aldehyde (Faglu) histofluorescence for catecholamines in 2 micron sections using polyethylene glycol embedding.

A technique is described which couples the aqueous aldehyde fluorescence (Faglu) method [5,6] with polyethylene glycol (PEG) embedding to obtain sections of brain as thin as 2 microns for light microscopic examination. Blocks from rat brains perfused with Faglu solution were embedded in PEG, sectioned on a rotary microtome and examined for amine fluorescence. Both catecholaminergic perikarya and their terminal arborizations were observed with high resolution in 2 micron sections. Single neurons could be traced in serial sections and varicosities as well as intervaricose segments were visible in terminal regions. This technique offers the further advantage of fixation compatible with electron microscopy, immunohistochemistry and other neuroanatomical methods. PEG-embedding of Faglu-fixed tissue thus provides a useful addition to existing fluorescence histochemical techniques for the visualization of catecholamines.