Measuring cellular forces within living embryonic tissues

Cell-generated mechanical forces play a critical role during tissue morphogenesis and organ formation in the embryo. Despite their relevance in sculpting functional embryonic structures, very little is known about the mechanisms by which cellular forces affect/control developmental processes, mainly because it has not been possible to measure cellular forces within developing tissues in vivo. In this talk, I will present a new technique that permits direct quantification of cellular mechanical stresses in situ within living tissues and developing organs. Using this novel technique, we quantify the stresses generated by mammary epithelial cells cultured within 3D aggregates (3.4 nN/µm²) and confirm that these stresses are dependent on myosin II activity and more than two-fold larger than the stresses generated by cells of embryonic tooth mesenchyme when analyzed within similar cultured aggregates or in developing whole mouse mandibles.