organs are also polarized in a plane vertical to the A/B axis. Recent studies indicate that this
so-called planar cell polarity (PCP) plays an essential role in the formation of multiple organ
systems regulating directed cell migrations, polarized cell division and proper differentiation.
In this review we will discuss the molecular mechanisms regulating PCP, including the
hypothesized roles for Wnt ligands in this process, and its roles in vertebrate organogenesis.