Morphodynamics of the nervous system in the regenerative processes of Convoluta convoluta (Turbellaria, Acoela)]

By means of the method for revealing cholinesterases the alterations in the nervous system of Convoluta convoluta after mechanical lesion were studied. After a transversal transection of the animal into two pieces the anterior part of the body acquired the normal form within 3-4 days; the nervous system underwent inconsiderable transformations associated with a formation of a plexus in the injured area. The posterior parts of the body regenerated slowly. During the first days disintegration of the resting parts of the nervous system was observed. Later on the diffuse cholinesterase activity suggesting the beginning of the brain formation was manifested in the wound field. Plexus strands "grow" in the caudal direction from the brain in parallel with its development. Within three weeks the nervous system of the animals which had restored their mouth opening, body shape and normal behaviour consists of the brain and plexus not arranged in nervous trunks. The reaction of the nervous system to the ablation of a part of the brain and to a continuous mechanical injury were studied. The data obtained show a high morphological lability of the nervous system of Convoluta convoluta, its ability to radical structural rearrangements.