DEPARTMENT COLLOQUIUM | Self-Organization in Animal Development and the Physics of Active Foams

Developmental biology presents some of the most amazing examples of self-organization found in nature: Starting from a single-celled egg, an animal is able, largely without outside help, to construct an entire, incredibly intricate organism, with cells of different types taking on myriad shapes and arranged in complex patterns to create a viable adult. Many of the individual steps in this maturation bear at least a superficial resemblance to pattern formation or self-assembly in simpler physical systems, and there is a long tradition of using physically-inspired models to try to understand developmental processes. Using examples from my own research on cell packing in the fish retina, I will show how it is becoming possible to dissect the mechanisms of self-organization during development and illustrate some of the surprising new physical ideas that can result from such investigations. In particular, I will argue that cells packed together two-dimensional sheets behave in many ways like the bubbles in a foam, but with the crucial difference that the cells can exert active stresses that break rotational symmetry.