Tracking the Regenerative Growth in Earthworm: A Cellular and Molecular Perspective

Regeneration in earthworm is studied vastly and proved to be an effective model to study regeneration. The process of regeneration is a stepwise and gradual process. The mechanism of regeneration was not clear earlier but it was deciphered later. Regenerative growth occurs firstly by wound healing followed by blastema formation. Blastema cells are majorly derived from the existing tissue specifically longitudinal muscle cells near the amputation site by dedifferentiation. Differentiation and pattern formation are the major processes in early development and organogenesis and these involve activation of various molecular signaling pathways. Neural factors are also activated along with other transcription factors for neural development. Segmentation and pigmentation occur at the last stage of development. Survival rate and body weight after amputation also has a correlation with regenerative growth. Genetic regulation and signaling controls the development and growth via various controlling genes such as distal less, notch. These genes are responsible for blastema formation, organogenesis and patterning. Pluripotent factors such as nano, regulate the dedifferentiation to form pluripotent stem cell for blastogenesis. Further studies are needed to study molecular mechanism for regulation in earthworm regeneration.