Competing adhesions rigidify the vertebrate body axis*

Solidification of the presomitic mesoderm (PSM), an axial tissue of developing vertebrate embryos, is required for

healthy vertebrate body axis elongation. Failure of the PSM to solidify in zebrafish leads to delayed development and

bilateral asymmetry, such as curved tails. It has been found that in cadherin loss-of-function mutants, where cells do

not form cadherin-based cell-cell adhesions, the PSM has reduced cell packing fraction and yield stress. Despite the

reduced tissue integrity in cadherin mutants, we show that the PSM can still solidify in the absence of cell-cell

adhesion. We propose that the cadherin mutants experience increased integrin-based interactions between cells and

the extracellular matrix (ECM) that partially rescues tissue integrity. We develop numerical simulations using the

deformable particle model to investigate the relative contributions of cell-cell and cell-ECM adhesions to tissue

integrity. Our work shows that both cell-cell and cell-ECM adhesion are sufficient for tissue solidification, although

their molecular and physical mechanisms are different.