Our laboratory uses the sea cucumber Holothuria glaberrima, as a model system to study the cellular and molecular basis of organogenesis and regeneration. Sea cucumbers are coelomate organisms, members of the phylum Echinodermata. They are closely related to the chordates but, in contrast to these, exhibit an impressive ability to regenerate complex structures. In holothurians, the regenerative process is evidenced following evisceration in which all major viscera are discarded. We have studied the cells associated with regeneration, particularly those involved in neuronal and muscle regeneration. We have also identified constituents of holothurian ECM and the remodeling that occurs during the regeneration process. Similarly, we have studied matrix metalloproteases and determined changes in their activities during intestinal regeneration. Our ongoing experiments focus on the molecular aspects of regeneration, specifically on the genes that are important for the regeneration process to occur. We have already identified and characterized several genes involved in holothurian intestinal regeneration using PCR, differential display and subtractive hybridization, and are in the process of preparing microarrays. With these tools in place and using this novel model system we expect to achieve the long-term goal of our laboratory of characterizing the gene activation pathway involved in organ regeneration.