ULTRASTRUCTURAL-LOCALIZATION OF PANCREATIC POLYPEPTIDE AND FMRFAMIDE IMMUNOREACTIVITIES WITHIN THE CENTRAL-NERVOUS-SYSTEM OF THE NEMATODE, ASCARIS-SUUM (NEMATODA, ASCAROIDEA)

A post-embedding immunogold technique has been used to examine the sub cellular distribution of immunoreactivities to vertebrate pancreatic p olypeptide (PP) and to the invertebrate peptide, FMRFamide within the central nervous system (CNS) of the nematode, Ascaris suum. Gold label ling of peptide was localized exclusively over dense-cored vesicles wi thin nerve cell bodies, nerve axons and nerve terminals of the main ga nglia and nerve cords in the CNS. Double-labelling of peptides demonst rated an apparent co-localization of PP and FMRFamide immunoreactiviti es in the same dense-cored vesicles, although populations of dense-cor ed vesicles that labelled solely for FMRFamide were also evident. Anti gen preabsorption studies indicated little or no cross-reactivity betw een the two antisera.