Eur J Anat, 6 (3): 147-152 (2002)

Time-course of the regeneration of the earthworm cerebral ganglion with special reference to serotonergic elements

Lubics A., Reglodi D., Szelier M., Lengvari I.

Department of Anatomy, University of Pécs, Medical School, Szigeti u 12, 7624 Pécs, Hungary

ABSTRACT In the present study we give a detailed description of the time-course of regeneration following the removal of the cerebral ganglion in the earthworm, Eisenia fetida. Cerebral ganglia were removed by cutting the circumpharyngeal connectives and regeneration was examined at different time intervals by serotonin immunohistochemistry. The number of serotonergic fibers gradually increased between days 3-6, rebuilding the neuronal network of the cerebral ganglion. By day 10, the scar tissue was filled with an interwoven fiber network, which clearly outlined the central neuropil of the cerebral ganglion. The first immunoreactive nerve cells appeared on the 25^th day following the removal of the cerebral ganglion. According to our observations, the cerebral ganglion regains its original structure 70 days after removal. It can be suggested based on our results that the cerebral ganglion mainly regenerates from the subesophageal ganglion through the circumpharyngeal connectives.

Keywords: animal model, article, brain ganglion, earthworm, nerve cell network, nonhuman, regeneration, scar, serotoninergic system