CYTOCHEMICAL OBSERVATIONS ON THE NERVOUS-SYSTEM OF ADULT CORRIGIA-VITTA

Adult Corrigia vitta (Trematoda: Dicrocoelidea) inhabit the pancreatic duct of the fieldmouse. Apodemus sylvaticus, where, in numbers, they may occlude the duct lumen and prevent the flow of pancreatic secretio ns. Enzyme histochemical and immunocytochemical techniques. in conjunc tion with confocal scanning laser microscopy, have been used to examin e the localization and distribution of cholinergic. serotoninergic (5- HT, serotonin) and peptidergic components of the nervous system of the adult worm. All three classes of neuronal mediator showed a common pa ttern of staining, occurring throughout the central and peripheral ner vous systems. Of the four peptide immunoreactivities (IR) demonstrated (pancreatic polypeptide (PP), peptide YY (PYY), substance P (SP), FMR Famide), PP-IR was the most predominant, occurring not only within the central ganglia and longitudinal nerve cords, but also in subtegument al plexuses and in fibres associated with the egg-forming apparatus. P YY and FMRFamide IRs were evident throughout the central and periphera l nervous systems: FMRFamide immunostaining, in particular, highlighte d innervation of the ootype and immunoreactive cell bodies around the Mehlis' gland. Both SP- and 5-HT-IRs were restricted to the cerebral g anglia, ventral nerve cords and associated cell bodies. The distributi on patterns of these peptides and 5-HT within the nervous system of C. vitta suggest they are likely to function as neuronal mediators. PP, PYY and FMRFamide may also serve in regulating egg production.