BELY, A.E.*; WEISBLAT, D.A.: Cellular origins of regenerated structures in the annelid Tubifex tubifex

The ability to regenerate lost body parts varies dramatically between different animals, sometimes even between closely related species. Among annelids, for example, leeches are incapable of regenerating any lost segments, while many oligochaetes are capable of extensive regeneration. It is likely that these differences in regeneration ability reflect, at least in part, species differences in the ability to contribute undifferentiated cells to form a blastema. Using a variety of methods, we are working to identify the cell populations that contribute to regenerated tissue in the oligochaete Tubifex tubifex . We are injecting lineage tracers into identifiable embryonic cells in order to determine the contribution of these labeled cells to regenerated structures. We are also performing analyses of BrdU incorporation to identify mitotically active tissues that potentially contribute cells to regenerated structures.