Fluid dynamics of establishing left-right patterning in development

How does the clockwise motion of tens of monocilia drive a leftward flow in the node? And, as the observed flow is leftward, how is the fluid recirculating within the node, as it must, because the node is a closed structure? How does the nodal flow lead to left–right symmetry breaking in the embryo? These questions are within the realm of fluid physics, whose application to the problem of left–right symmetry breaking in vertebrates has led to important advances in the field. Birth Defects Research (Part C) 84:95–101, 2008. © 2008 Wiley‐Liss, Inc.