Biology Reference
In-Depth Information
FIGURE 26.8
Behaviour of the model of Merks et al. under different degrees of contact inhibition of motility.
Cells begin in a random scatter (a) and, when there is no contact inhibition (b), they form islands; whereas, with
contact inhibition (c), they form plexus-like networks. (d) Islands branch, when contact inhibition is active. (e) When
the model is run with different amounts of contact inhibition (in other words, ratios of motility between bulk cells
and edge cells), there is a fairly steep transition between island formation and branch formation. This figure is
sketched from original data in Merks et al.
19
strengths of contact inhibition (that is, different ratios between the motility parameter at
a cell-cell boundary and at a cell-matrix boundary), revealed a rather steep switch between
the two types of behaviour (
Figure 26.8
.e). The fundamental reason for this change is that,
with contact inhibition active, cells in the centre of an island show little motility whereas
those at the edge show plenty. Motility is greater on the free edge, but directionally, chemo-
taxis means that cells still 'want' to move inwards. That is, the probability of a free edge
displacement up-gradient (
Figure 26.9
a) is higher than that down-gradient; this can mean
free-edge retraction. Given a cell's overall resistance to compression (the 'energy' term in
