Cell recruitment may work as a temporal controller of size in the Drosophila wing

A fundamental question in developmental biology is how organs robustly attain a final size despite perturbations in cell growth and proliferation rates. Since organ growth is an exponential process driven mainly by cell proliferation, even small variations in cell proliferation rates, when integrated over a relatively long time, will lead to large differences in size, unless an intrinsic control mechanism compensates for these variations. Here, we use a mathematical model to propose the hypothesis that in the developing wing of Drosophila, cell recruitment, a process in which undifferentiated neighboring cells are incorporated or recruited into the wing primordium, determines the time in which growth is arrested in this system. As a consequence, perturbations in proliferation rates of wing-committed cells are compensated by an inversely proportional growth time to ensure a robust size of the wing. Furthermore, we show that growth control is lost when fluctuations in cell proliferation affects both wing-committed and recruitable cells. Our model suggests that cell recruitment may act as a temporal controller of growth to buffer fluctuations in cell proliferation rates and offers a plausible solution to a long-standing problem in the field.