Fig. 4

2D spatial distribution plots of PH3-positive cells during craniofacial development in C. perspicillata. A maximum intensity projection (MIP), obtained from an aligned stack of 2D sagittal sections for a CS17 embryo head, is shown in lateral view. All extracted X, Y coordinates from 2D image stacks are plotted as 2D distribution plots, oriented in lateral view. Thus, X axis relates to anterior–posterior position and the Y axis relates to dorsal–ventral position. All lateral images are oriented such that the anterior face points to the right and the back of the head points to the left. The intensity of purple color highlight concentrated regions of proliferation. At CS16, the majority of proliferation is localized to the forebrain. From CS17–CS24, growth zones appear in the midface, basicranium, hindbrain and forebrain