Structure of the prostomial appendages and the central nervous system in the Protodrilida (Polychaeta)

摘要: The prostomial appendages and the central nervous system have been investigated by electron microscopy in Protodriloides chaetifer, P. symbioticus, Protodrilus haurakiensis, oculifer, ciliatus, helgolandicus, adhaerens, Saccocirrus krusadensis S. papillocereus. tentacles are highly developed, mobile sensory structures consist of cuticle, epidermis, a different number intraepithelial nerves, small blind-ending blood vessel bundle longitudinal muscle fibres. An internal canal is only present species. On seven types cells found including multiciliated uniciliated with cilia penetrating non-penetrative cilia, phaosomes basal ciliated cells. latter described for first time polychaetes. From specific pattern innervation up to five nerves originating close brain from dorsal ventral roots circumoesophageal connectives it evident that represent palps. In palps nerve fibres form neuroneuronal, myoneuronal epithelioneuronal synapses. also gives rise stomatogastric various nerves. palp canals separated surrounding tissue prominent extracellular matrix. wall formed centre usually completely filled cell bodies these large coelenchyme-like These move freely they very likely structural basis hydroskeletal function canals. other body cavities fluid probably driven into vascular via podocytes located zone prostomium. particular, structure its compared those polychaetes special emphasis Spionida, taxon presumed include sister group Protodrilida.