Abstract Lesions of the perineurium of the buccal ganglia of Helix pomatia have been found to elicit changes in neuronal arborizations. These changes were studied by light and electron microscopical techniques. In ganglionic regions of a damaged perineurium, the known arborizations of the identified neurones B1, B2 and B3 were characterized by additional and atypical fibres of small diameters and with multiple swellings. Damaged regions contained an increased number of neuronal fibres often showing vacuoles of great diameters. The changes observed 4–24 h after the damage of the perineurium are interpreted as neuronal sproutings.