Two rotating cilia in the node cavity are sufficient to break left-right symmetry in the mouse embryo

Nat Commun. 2012 Jan 10;3:622. doi: 10.1038/ncomms1624.


Determination of left-right asymmetry in mouse embryos is achieved by a leftward fluid flow (nodal flow) in the node cavity that is generated by clockwise rotational movement of 200-300 cilia in the node. The precise action of nodal flow and how much flow input is required for the robust read-out of left-right determination remains unknown. Here we show that a local leftward flow generated by as few as two rotating cilia is sufficient to break left-right symmetry. Quantitative analysis of fluid flow and ciliary rotation in the node of mouse embryos shows that left-right asymmetry is already established within a few hours after the onset of rotation by a subset of nodal cilia. Examination of various ciliary mutant mice shows that two rotating cilia are sufficient to initiate left-right asymmetric gene expression. Our results suggest the existence of a highly sensitive system in the node that is able to sense an extremely weak unidirectional flow, and may favour a model in which the flow is sensed as a mechanical force.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biophysics / methods
  • Body Patterning / genetics*
  • Cilia / physiology*
  • Developmental Biology / methods
  • Embryo Culture Techniques
  • Embryo, Mammalian / metabolism*
  • Embryo, Mammalian / physiology*
  • Gene Expression Regulation, Developmental
  • Methylcellulose / chemistry
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred ICR
  • Models, Biological
  • Mutation
  • Organizers, Embryonic / physiology
  • Time Factors


  • Methylcellulose