The GAIF-Positive Population of Neurons in the Evolution of the Temnocephalida

摘要: The nervous system of three species the Temnocephalida has been studied using GAIF method (which in small flatworms mostly reveals sensory catecholaminergic neurons). These represent evolution from primitive “turbellarian-like” temnocephalids to most specialised ones with tentacles and a sucker. numbers positions GAIF-positive neurons are invariant within each do not change hatching full maturity. A characteristic unpaired neuron contributing innervation anterior margin body is present all species: such cell previously found only marine Thalassovortex tyrrhenicus (Dalyellidae) which confirms close relationships between these taxa. Our series shows (i) reduction number perikarya associated lateral cords on ventral side body, probably related loss ciliary locomotion (the shift passive hunting looping locomotion) (ii) reinforcement end begins play an important role capturing prey. retention medial nearly identical sets Diceratocephala boschmai Craspedella pedum (rather different morphology) give first indication (in Plathelminthes) persistence homologous through significant evolutionary transformations organs they innervate.