Distinguishing Right from Left In most vertebrates during embryonic development, rotational movement of the cilia within a structure in the embryo, known as the node, generates unidirectional flow required for future left-right asymmetry of the internal organs. The flow may transport a determinant molecule or provide mechanical force. However, it is not clear how the flow is sensed. Yoshiba et al. (p. 226 , published online 13 September; see the Perspective by Norris and Grimes ) show that nodal flow in mouse embryos is sensed by the cilia of perinodal cells located at the edge of the node, in a manner dependent on Pkd2, a Ca 2+ -permeable cation channel that has been implicated in polycystic kidney disease in humans.

Cilia at the Node of Mouse Embryos Sense Fluid Flow for Left-Right Determination via Pkd2