Asymmetric Rotational Stroke in Mouse Node Cilia during Left-Right Determination

TL;DR

This study investigates the asymmetric rotational movement of mouse embryo cilia and how their tilting and driving force contribute to leftward fluid flow crucial for left-right body axis determination, combining experiments with computational modeling.

Contribution

It reveals that cilia generate asymmetric driving forces influenced by tilting angles, enhancing understanding of fluid flow mechanisms in embryonic development.

Findings

Leftward stroke more effective due to asymmetric driving force.

Cilia tilting and open angle determine force asymmetry.

Computational and experimental methods combined.

Abstract

Clockwise rotational movement of isolated single cilia in mice embryo was investigated in vivo. The movement 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 posterior side. Because of the no-slip boundary condition at the cell surface, the upper stroke away from the boundary generates leftward flow, and the lower stroke close to the boundary generates slower rightward flow. 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 force. Our results suggest that the driving force is asymmetric and that it is determined by the tilting angle and open angle of the rotating cilia. Specifically, it is maximized in the leftward stroke when the cilia moves comparatively far from the boundary.