Active cell and ECM movements during development.

Dynamic imaging of the extracellular matrix (ECM) and cells can reveal how tissues are formed. Displacement differences between cells and the adjacent ECM scaffold can be used to establish active movements of mesenchymal cells. Cells can also generate large-scale tissue movements in which cell and ECM displacements are shared. We describe computational methods for analyzing multi-spectral time-lapse image sequences. The resulting data can distinguish between local “active” cellular motion versus largescale, tissue movements, both of which occur during organogenesis. The movement data also provide the basis for construction of realistic biomechanical models and computer simulations of in vivo tissue formation.