17 October 2014
Ray Keller
Department of Biology
University of Virginia
Embryonic tissues are reshaped dramatically in early development by the physiologically and mechanically integrated activities of hundreds, even thousands of cells. One of the most common of these coordinated cell movements is convergent extension, in which an active, polarized intercalation of cells causes shortening of a tissue in one dimension (convergence) and concomitant lengthening in one or both of the transverse dimensions (by convention, called convergent extension or convergent thickening). I will discuss several concepts about how local cell motility or shape change is thought to bring about an active, force-producing cell intercalation in both epithelial and in mesenchymal cell systems. I will focus on how these concepts are challenged by recent findings in our lab and in others about cell adhesion, the cytoskeleton, the types and patterns of cell behavior, and forces generated at the cell and tissue level. The emerging picture of this "morphogenic beast" may be one of diversity at many levels, all in service of a fundamental biomechanical principle, one that is conserved and exploited in many contexts, from the intercalation of cells in embryos to intercalation of pigs trying to keep warm on a cold night.