Animal tissue and organ development requires the orchestration
of cell movements, including those of interconnected cell groups,
termed collective cell movements. Such movements are incredibly
diverse. Recent work suggests that two core cellular properties,
cell-cell adhesion and contractility, can largely determine
geometry, packing, sorting, and rearrangement of epithelial
cell layers. Two additional force-generating properties, the
ability to generate cell protrusions and cell adhesion to the
extracellular matrix, contribute to active motility. These mechanical
properties can be regulated independently in cells, suggesting
that they can be employed in a combinatorial manner. A small
number of properties used in combination could, in principle,
generate a diverse array of cell shapes and arrangements and
thus orchestrate the varied morphogenetic events observed during
metazoan organ development.
