Fig. 10.

$g_{\mathit{\theta }c}$ versus $R_0/d$ with stiff ($c=10$) and soft ($c=0.1$) neighbourhood without net growth ($J=1$) from the exact solution. For large $R_0/d$, $g_{\mathit{\theta }c}$ is very close to $1$, indicating slight contraction without growth contributes to the instability. As $R_0/d$ decreases, $g_{\mathit{\theta }c}$ decreases further for stiff neighbourhood but disappears for soft neighbourhood. This provides an explanation for the success of “purse string” closure during embryonic wound healing due to the flexibility of the surrounding tissue