  During development, cell fates are determined through a combination of
intracellular transcriptional regulations and extracellular signaling. As a
result, spatial patterns of different cell types arise. We investigate the
decision between epiblast and primitive endoderm cells in the inner cell mass
of the preimplantation mouse embryo. Our computational model uses global cell
signaling for the pattern formation. By varying the signal dispersion, cell
type arrangements ranging from a checkerboard to an engulfing pattern can be
generated. Pair correlation functions provide a well-suited way of
characterizing the model output. With these, we established a quantitative
comparison between the simulation results and experimental data of inner cell
mass organoids. We obtained an astonishing agreement. Thus, our model proves
its capability to replicate the cell differentiation patterns, making global
signaling a strong contender to explain pattern formation in the
preimplantation embryo.
