Final answer:
Kupffer's node cilia create a leftward flow of signals, which is crucial for the left-right asymmetry during embryonic development.
Step-by-step explanation:
The nodal cilia in Kupffer's node create a leftward flow of signals, often referred to as 'nodal flow.' This flow is important during embryonic development as it establishes the left-right axis of the organism. The rotational movement of the monocilia on the cells in Kupffer's node generates a directional fluid flow, which is interpreted by the surrounding embryonic tissues and leads to the asymmetric development of certain organs and structures in the body.