Influence of the Supra-oesophageal Ganglion on Posterior Regeneration in Nereis diversicolor

Abstract

Extirpation of the supra-oesophageal ganglion of N. diversicolor before the removal of a number of posterior segments inhibits the formation of new segments. At most, a new pygidium is regenerated. Extirpation of the supra-oesophageal ganglion 3 days after the removal of a number of posterior segments retards but does not inhibit segment-formation. An increase in the quantity of neurosecretory material produced by cells in certain nuclei of the brain of regenerating worms becomes detectable about 12 hours after the posterior segments have been removed. Nereis resembles lumbricid oligochaetes in that the supra-oesophageal ganglion plays an essential role during the initial phases of regeneration, but that once regeneration is initiated, its importance declines.