Histochemical evidence of the catecholamine-associated nervous system in certain schistosome cercariae.

The localization of catecholamines was documented in the cercaria of Schistosoma mansoni and S. japonicum by a fluorescent histochemical method using glyoxylic acid (GA). Cell bodies and nerve fibres were spatially visualized in whole-mount preparations, and the fluorescent traces were investigated. The nervous system was bilaterally symmetrical, showing a similar formation in both species. A pair of cerebral ganglia with a transverse commissure showed a complex network of fluorophores, and each radiated two sets of anterior and posterior longitudinal nerve cords. A third pair of longitudinal nerve cords was observed in the most dorsal area. A posterior transverse commissure was seen to connect the posterior longitudinal cords, and the posterior terminals of the postero-ventral cords communicated with the tail cords. The glyoxylic acid-induced fluorescence (GAIF) method was demonstrated to be quite suitable for neuroanatomical and neurophysiological investigations of larval forms.