All living things are shaped by physical forces. Such forces range from those operating on the nanometer-scale of protein protein interactions to those that operate on the whole organism-scale, enabling organisms to interact with their environment. During development and growth of multicellular organisms, forces at the cell- and tissue-scale drive morphogenesis. The magnitude and direction of these forces, and the structures they act upon, are the products of evolution including gene regulatory networks and the molecular machinery they encode. Gene regulatory networks establish the architectural blueprints of the embryo while molecular machinery forms materials and motors to assemble the body.
In this presentation, I will relate recent studies on the mechanics of development that are beginning to expose the roles of physical forces in shaping multicellular organisms. Physical work at the cellular level is the product of cycles of actomyosin contractility and F-actin polymerization. The forces produced by these multicellular collectives are remarkably small and are just sufficient to shape ultra-soft tissues of the early embryo. I will discuss how the cytoskeleton generates these forces and also how its composition regulates the ultrasoft properties of the early embryo. As germ layers are formed and the proper body of the embryo is established, the resulting complex heterogeneous microenvironment provides novel positional cues that guide cell identity and cell behaviors critical to the success of subsequent waves of morphogenesis.
Finally, I will discuss how efforts to understand the physics of morphogenesis in the embryo provides insights to the progression of human disease and lessons for new generations of tissue engineers.