SEROTONIN AND NEUROPEPTIDE FMRFAMIDE IN THE NERVOUS SYSTEM OF <i>OPISTHIOGLYPHE RANAE (TREMATODA: PLAGIORCHIIDAE). </i>AN IMMUNOCYTOCHEMICAL STUDY
The presence and localization of the serotoninergic and FMRFamidergic structures in the nervous system of the trematode <i>Opisthioglyphe ranae</i>, the marsh frog intestinal parasite, was studied using immunocytochemistry. The serotonin-immunoreactive nerve cells and fibers were revealed in the head ganglia, circular commissure, longitudinal nerve cords and their connective commissures, as well as around the oral and ventral suckers, oesophagus and genital pore. FMRF-specific immunoreactivity was observed in the head ganglia, longitudinal nerve cords and terminal parts of the reproductive system. The results obtained are discussed in light of the available data on the presence and functional significance of the above-mentioned neurotransmitters in trematodes.