In-vitro differentiation of embryonic stem cells into defined cell types is a field of immense importance for both regenerative medicine and for basic understanding of development. Promising clinical uses include generation of hepatocytes for treatment of liver failure and generation of cardiac progenitor cells or cardiomyocytes for treatment of acute coronary disease. Embryoid bodies (EB's), three dimensional aggregates of differentiating embryonic stem cells, have been the method of choice for in-vitro differentiation into several cell types, including motor neurons, hepatocytes and cardiomyocytes.I suggest a high-throughput live cell imaging approach for the study of EB differentiation dynamics. I will develop a microfluidic-based system for controlled EB formation, for generation and imaging of both uniform and variable size and shape EB’s. I will study correlates of specific cell fate differentiation and cell movement patterns by imaging large numbers of such systems, in conjunction with protein reporter and lineage tracing fluorescent constructs. I will focus on the conditions for appearance of cardiomyocytes: supporting cell types, spatial characteristics and signaling events. The project will enhance our basic understanding of cell movement and rules of differentiation during early development, and can lead to improved protocols of in-vitro differentiation.