Microscopy images from: A cadherin-integrin-ECM code for presomitic mesoderm fluidity

Animal tissues exist within a continuum of fluid to solid states, and
transitions between states are important for embryonic development, wound
healing and cancer metastasis. Fluid to solid transitions are governed by
the ratio of adhesive energy to kinetic energy. Here, we find that
presomitic mesoderm solidification is driven by an intrinsic decline in
cell speed along with an increase in adhesion mediated by Cadherin 2 in
parallel with Fibronectin and its receptor Integrin α5. A computational
model of cell-cell adhesion in the central tissue mesenchyme and cell-ECM
adhesion on the tissue surface explains the observed phenotypes. Further,
we identify negative feedback within the ECM as Fibronectin supports the
formation of a separate layer of Fibrillin 2b matrix that inhibits
solidification. These data reveal a tissue fluidity code in which
solidification is promoted by cadherins in parallel with Integrin α5 and
Fibronectin, whereas negative feedback through Fibrillin 2b promotes
fluidization.