Immunomicroscopical observations on the nervous system of adult Eudiplozoon nipponicum (Monogenea : Diplozoidae)

Neuronal pathways have been examined in adult Eudiplozoon nipponicum (Monog enea: Diplozoidae). using cytochemistry interfaced with confocal scanning l aser microscopy, In an attempt ru ascertain the status of the nervous syste m. Peptidergic and serotoninergic innervation was demonstrated by indirect immunocytochemistry and cholinergic components by enzyme cytochemical metho dology: post-embedding electron microscopical immunogold labelling revealed neuropeptide immunoreactivity at the subcellular level. All three classes of neuronal mediators were identified throughout both central and periphera l elements of a well-differentiated orthogonal nervous system. There was co nsiderable overlap in the staining patterns for cholinergic and peptidergic components, while dual immunostaining revealed serotonin immunoreactivity to be largely confined to a separate set of neurons. The subcellular distri bution of immunoreactivity to the flatworm neuropeptide. GYIRFamide, confir med neuropeptide localisation in dense-cored vesicles in the majority of th e axons and terminal varicosities of both central and peripheral nervous sy stems. Results reveal an extensive and chemically diverse nervous system an d suggest that pairing of individuals involves fusion of central nerve elem ents; it is likely also that there is continuity between the peripheral ner vous systems of the two partner worms. (C) 2001 Australian Society for Para sitology Inc. Published by Elsevier Science Ltd. All rights reserved.