Fig. 5

Growth zones and their spatial heterogeneity. Growth zones in the forebrain (blue), the anterior midface (light blue), the posterior midface (purple), and the basicranium (light purple) were investigated in our model bat C. perspicillata. A circular region with a radius of 550 μm across the four growth zones (a) were evaluated by nearest neighbor distance (NND) (b) and a Monte Carlo significance Goodness-to-fit test (F-function) (c). NND distribution between cells are shown as histograms. The mean NND is 26 μm in the anterior midface (n = 364), 27 μm in the posterior midface (n = 398), 20 μm in the forebrain (n = 570), and 42 μm in the basicranium (n = 147). Spatially, cells of the anterior midface, posterior midface and forebrain are distributed similarly. In the basicranium, cells are distributed homogenously. Pairwise comparisons between all regions using Wilcoxon rank sum test reveal the anterior and posterior midface have similar mean NND (p = 0.47), but the NND between other regions are unique (p < 2e−16) (b). For each growth zone, the distribution of PH3 cells were independently assessed (magenta lines in c). The estimated random F-function by Monte Carlo simulations (black line) and the 95% envelope (dotted black lines) describe random proliferation patterns. Deviations from randomness fall outside the 95% envelop and describe a structured proliferation pattern consistent with clustering (forebrain and midface). Deviations within the 95% envelop describe spatial randomness (basicranium) (c)