Caudal regeneration in Tubifex tubifex (Oligochaeta, Tubificidae) following copper exposure

Abstract. The oligochaete, Tubifex tubifex (Oligochaeta, Tubificidae), is capable of the auto-tomization and regeneration of missing body parts. The posterior end of the worm is subject to autotomy (e.g., after predation or after exposure to toxic substances) and can be regenerated thereafter. Despite the ecological importance of T. tubifex , processes of autotomy and regeneration have been little studied. This work describes daily morphological and histological observations of caudal regeneration of this worm. We also compared regeneration processes when autotomy was induced by artificial transsection of the worms (control worms) and by exposure to copper ion, a frequently encountered environmental contaminant. The worms regenerated a functional posterior end (defecation possible) in 7 d as well as a prepygidial zone from which new segments could be regenerated. In T. tubifex , regeneration involved the presence of activated mesoblastocytes in the worm, increased number of neoblasts, and the increased migration of these cells. However, Cu²⁺ did not affect these processes, since no difference could be detected between regeneration of control and Cu-autotomized worms.