ИСТИНА

Ctenostomе bryozoans are unusual gymnolaemates and their anatomy probably reflects ancestral state of bryozoans in general. Our research is focused on the peculiarity of the lophophore innervation in Flustrellidra hispida. Immunocytochemistry and confocal laser scanning microscopy revealed the presence of outer nerve ring, which gives rise to the tentacle nerves that are associated with the groups of outer perikarya. The outer nerve ring has been formerly described in some ctenostomates and cyclostomates, but is not connected with tentacle nerves. Formerly, the outer nerve ring was described in some ctenostomates and cyclostomates, but it has no connection to any nerves. The discovered feature of lophophore innervation of F. hispida allows to suggest the evolutionary transformation from a phoronida-like ancestor lophophore, bearing prominent outer nerve ring with numerous tentacle nerves emanating from it, to the complicated bell-shaped lophophore of F. hispida with well pronounced outer nervous ring bearing a few tentacle nerves. Next one in this hypothetical row will be the lophophore of the other ctenostomates and some cyclostomates with an outer nerve ring having no connection to any nerves, and cheilostomates lophophore, lacking an outer nerve ring at all. The study is supported by Russian Science Foundation (#18-14-00082).