Migration of activator peaks in the transversal direction.

<p>(<b>a</b>) snapshot of YS domain (the YS domain is growing over time as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102718#pone-0102718-g007" target="_blank">figure 7</a>). Morphogen concentration is denoted as z-axis height. Substrate has relatively low values inside the growing rectangle, and relatively high outside the growing rectangle. Y equals to 1.0 inside the rectangle and equal to 0.0 outside that rectangle. The initial rectangular is 5 space steps wide by 10 space steps long. The length of the rectangular increases one space step every 10,000 time steps. Space step dx = 0.3, time step dt = 0.4dx². (<b>b, c</b>) profile of S along the dotted line as shown in panel a. The high/low value of S profile is 1.0/0.6 and 1.0/0.4 in panel b and c. Activator peaks migrate out of the YS domain in a left-right order and a symmetrical manner under condition b and c respectively.