Asymmetric rotational stroke in mouse node cilia during left-right determination.

Rotational movement of isolated single cilia in mice embryo was investigated, which generates leftward fluid flow in the node cavity and plays an important role in left-right determination. The leftward unidirectional flow results from tilting of the rotational axis of the cilium to the posterior side. By combining computational fluid dynamics with experimental observations, we demonstrate that the leftward stroke can be more effective than expected for cases in which cilia tilting alone is considered with the no-slip condition under constant driving torque. Our results suggest that the driving torque is asymmetric.