Secondary and tertiary formation depends on cell death.

<p>(<b>A</b>) Image captured at 50,000 MCS from a simulation of reduced cell death (L = 12) showed numerous ectopic, end-to-end 2°-like cells (•) and vertices with three cells in the 3° locus (arrows). Asterisk labels an ommatidium enlarged in inset. (<b>B</b>) Graph showing the decrease in cell number over time for different levels of cell death. L controlled the ‘strength’ of cell death as described in <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1000841#s2" target="_blank">Results</a>. Cell death was initiated at 10,000 MCS and each line represents the result of a single representative simulation from at least two repetitions. (<b>C</b>) Graph showing formation of 2°s over time for different levels of cell death. Each line represents the result of a single representative simulation from at least two repetitions. (<b>D</b>) Graph showing formation of 3°s over time for different levels of cell death. Each line represents the result of a single representative simulation from at least two repetitions. (<b>E</b>) Graph showing number of both 2° and 3°s at 15,000 MCS as cell death parameters are changed to increase the total cell number. Each point represents a different cell death parameter in the simulations from (B), (C) and (D).</p>