This Presidential Young Investigator award is to support research on embryogenesis. The PI is interested in how embryonic cells change position to arrive at the right place at the right time. She is interested in the movement of groups of cells and of individual cells and has developed the killlifish as an experimental model for the investigation of these migrations. In the course of her previous studies she has demonstrated two as yet unrecognized phenomena-active epithelial cell underlapping as a mode of movement and controlled, geometric membrane turnover as a motive force. This research has fundamental importance to our understanding of how complex tissues, organs and systems arise from a few, diffuse undifferentiated cells.