  Cells undergo dramatic changes in morphology during embryogenesis, yet how
these changes affect the formation of ordered tissues remains elusive. Here we
find that the emergence of a nematic liquid crystal phase occurs in cells
during gastrulation in the development of embryos of fish, frogs, and fruit
flies. Moreover, the spatial correlations in all three organisms are
long-ranged and follow a similar power-law decay (y~$x^{-\alpha}$ ) with
$\alpha$ less than unity for the nematic order parameter, suggesting a common
underlying physical mechanism unifies events in these distantly related
species. All three species exhibit similar propagation of the nematic phase,
reminiscent of nucleation and growth phenomena. Finally, we use a theoretical
model along with disruptions of cell adhesion and cell specification to
characterize the minimal features required for formation of the nematic phase.
Our results provide a framework for understanding a potentially universal
features of metazoan embryogenesis and shed light on the advent of ordered
structures during animal development.
