Histological observations of blastema formation during earthworm tail regeneration

The earthworm is a unique and valuable model for investigating the mechanism of regeneration. We studied the developmental change in blastemal cells during earthworm tail regeneration. By histological observation, we have found that the major origin of earthworm blastemal cells is the longitudinal muscle layer of the body wall. The blastema formed beneath the wound dermis is segmented and becomes redifferentiated. The results obtained demonstrate that the blastema formation in earthworm tail regeneration provides a useful epimorphic model of regeneration.