The scientific questions arising from the ability of certain species, but not others, to massively regenerate their bodies are among the most fascinating and challenging confronting modern cell and developmental biologists today. The tremendous implications of this research area for human medicine and tissue engineering are obvious. Yet many other animals exhibit robust regenerative capabilities, including “lower” vertebrates such as amphibians, and invertebrates such as echinoderms, flatworms and annelids. In the extreme case, some species can reproduce vegetatively indefinitely. Such animals must contain the operational equivalent of immortal, totipotent somatic stem cells. From invertebrates to the higher vertebrates, their metabolic pathway, developmental regulatory genes, and intercellular signaling pathways are evolutionary conserved. With these, study on regeneration is an ingenious, powerful model system for studying the post-embryonic development and innate immunity mechanisms. Here, I will discuss the processes of immunemediated gut injury and regeneration using annelid regeneration model system.

• Sung-Jin Cho(Department of Biology, Chungbuk National University, Chungbuk 361-763, Republic of Korea)