Sequential transfer of left-right information during vertebrate embryo development.

The establishment of left-right asymmetries in the vertebrate embryo is carried out by complex genetic interactions that impart left- or right-sided information to the developing organs and structures. The origin of LR information is still unclear, but recent advances have provided new insights as to how it is relayed to the embryo node, and thereafter to the lateral plate mesoderm. In both steps, signaling by members of the transforming growth factor-beta superfamily plays critical roles in amplifying and spreading LR cues, which are reviewed here.