Fig 4

To determine the number of apoptotic cells in the developing embryo, immunohistochemical staining against Caspase3 is performed at 5 hpf, 7 hpf, and 9 hpf. a), After antibody staining, 10 areas of ca 20 by 20 cells are placed randomly over the dorsal hemisphere of the embryos (marked by gsc-GFP expression) and within these squares of ca 400 cells, the number of apoptotic cells is counted. b) At 5 hpf, no apoptotic cells are detected. At 7 hpf 2% and at 9 hpf 3% apoptotic cells are observed. c) Induced apoptosis of a similar relative number of cells as experimentally determined are implemented into our simulations. The simulation of cytoneme based Wnt-transport with weak sorting and no induced apoptosis (left) is compared to the simulation with additionally enabled induced apoptosis (right) at t = t_TRS = 180 min. Cell fates and coloring are as in Fig 1. d) Increasing the sorting parameter p_DirMig during the directed transport simulations leads to decreased mixing of cell fates (red with, blue without apoptosis). Even large values for p_DirMig, however, cannot remove truly isolated cells (cf. c)). Adding limited apoptosis (130 cells over entire simulation) can eliminate these cells and leads to an additional improvement. Displayed is the development after t = 180 min averaged over 10 simulations for each value of p_DirMig, with p_DirMig = 0.02 and p_DirMig = 0.2 (cf. Fig 4) highlighted.