Fig. 5.

Left-right patterning mechanisms are conserved from zebrafish to mouse. (1) Rotation of motile cilia in the left-right organizer (Kupffer's vesicle, zebrafish; node, mouse) causes the leftward flow of fluid that precedes asymmetric gene expression. (2) Spaw-Vg1 and Nodal-Gdf1 heterodimers are restricted to the left by Dand5/Cerl2 activity at the node. (3) Spaw/Nodal induces expression of spaw/Nodal in the left LPM, and (4) Spaw activity is maintained on the left by Lefty1-mediated inhibition. LPM, lateral plate mesoderm; N, notochord; KV, Kupffer's vesicle; Nd, node.