Conserved function for embryonic nodal cilia

A similar mechanism may underlie the handedness seen in all vertebrate body plans. How left–right handedness originates in the body plan of the developing vertebrate embryo is a subject of considerable debate1,2. In mice, a left–right bias is thought to arise from a directional extracellular flow (nodal flow) that is generated by dynein-dependent rotation of monocilia on the ventral surface of the embryonic node3,4. Here we show that the existence of node monocilia and the expression of a dynein gene that is implicated in ciliary function are conserved across a wide range of vertebrate classes, indicating that a similar ciliary mechanism may underlie the establishment of handedness in all vertebrates.