Место издания:The Technical University Liberec, Czech Republic
Первая страница:76
Аннотация:Neuroanatomy is traditionally used for phylogenetic reconstruction. Because the lophophore is the main feature of all lophophophorates, whose monophyly is recently actively discussed, neuroanatomy of the lophophore may help clarify the status of the Lophophorata and provide new information on the early evolution of the group. Original data on organization of the lophophore nervous system is obtained in several phoronids. Comparative analysis revealed the presence of homologous elements in the nervous system of the lophophore in phoronids and bryozoans. In species from both groups, the lophophore has several main nerves that are homologous. The dorsal ganglion of phoronids is homologous to the cerebral ganglion of bryozoans. The minor nerve ring of phoronids is homologous to the circum oral nerve of bryozoans. The tentacular nerve ring of phoronids is homologous to the outer nerve of ctenostome and cyclostome bryozoans. In phoronids and in bryozoans, there are intertentacular serotonin-like immunoreactive perikarya associated with the inner nerve ring. Tentacles are innervated from the intertentacular nerves, which start from the inner nerve ring. In both phoronids and bryozoans there are peritoneal neurites in the tentacles. These new results suggest the presence of two nerve centers and two nerve rings in the last common ancestor of phoronids and bryozoans. During evolution, bryozoans may have lost the outer nerve center and outer nerve ring, whereas phoronids may have lost the inner nerve center and inner nerve ring. These morphological results evidence the close relationship of phoronids and bryozoans, support the traditional view of the lophophorates monophyly, and contradict new concept of Polyzoa as clade that includes three phyla: Bryozoa, Entoprocta, and Cycliophora. This study is supported by Russian Science Foundation (#18-14-00082).
