Left-right asymmetry in vertebrates.

All vertebrates develop with a distinct, invariant, left-right (L-R) body asymmetry. Recently, a number of molecules have been shown to be expressed asymmetrically with respect to the L-R axis during early embryogenesis. The temporal expression patterns of these molecules, in combination with embryo manipulation and genetic experiments, indicate that they may represent elements of a conserved pathway governing embryonic handedness.