AN IMMUNOCYTOCHEMISTRY STUDY COMPARING THE OCCURRENCE OF NEUROACTIVE SUBSTANCES IN THE NERVOUS-SYSTEM OF CERCARIAE AND METACERCARIAE OF THEEYE FLUKE DIPLOSTOMUM-SPATHACEUM

The nervous system of two larval stages (cercariae, metacercariae) of eye fluke Diplostomum spathaceum was investigated immunocytochemically by the application of antisera to the amino acid glutamate and to neu ropeptides isolated from invertebrates (Mollusca) and from vertebrates to whole-mount preparations. In cercariae, positive immunoreactivity (IR) was observed with antisera raised against Catch-relaxing peptide (CARP), FMRFamide, alpha-caudodorsal cell peptide (alpha-CDCP), substa nce P, vasotocin, and vasopressin. In metacercariae, in addition to po sitive staining with these antisera, the ones raised against glutamate , APGWamide, caudodorsal cell hormone I(CDCH-I), and small cardiac pep tide B (SCPB) also gave positive IR in the nervous system. In the two larval stages the most extensive pattern of IR was observed with anti- FMRFamide and anti-CARP. In the nervous system of metacercariae the sa me immunoreactive neurosubstances appeared to be present as in that of cercariae. The increase in the variety of immunoreactive neurosubstan ces in the more complex nervous system of metacercariae is discussed i n relation to parasite development and to host adaptation.