Left-right asymmetry and the chick embryo.

Left-right (LR) asymmetry provides a fascinating example of the patterning of a major body axis during embryonic development. The chick embryo was the first system in which a molecular basis for left-right patterning was characterized, revealing that molecules known to play a role in other aspects of embryogenesis likewise are involved in the establishment of left-right asymmetry. The chick has been instrumental in the identification of a pathway of genes which regulate the sidedness of major body organs, as well as providing a basis for understanding laterality disturbances in twins. This review summarizes the advances in LR asymmetry which have been made in the chick system within the context of laterality research in general.