LAUSR

A fundamental question in developmental and stem cell biology concerns the origin and nature of signals that initiate asymmetry leading to pattern formation and self-organization. Instead of having prominent pre-patterning determinants as present in model organisms (worms, sea urchin, frog), we propose that the mammalian embryo takes advantage of more subtle cues such as compartmentalized intracellular reactions that generate micro-scale inhomogeneity, which is gradually amplified over several cellular generations to drive pattern formation while keeping developmental plasticity. It is therefore possible that by making use of compartmentalized information followed by its amplification, mammalian embryos would follow general principle of development found in other organisms in which the spatial cue is more robustly presented.What breaks symmetry in early mammalian embryonic development has been much questioned. Here, Magdalena Zernicka-Goetz and colleagues propose that compartmentalized intracellular reactions generate micro-scale inhomogeneity, which is amplified in the developing embryo, driving pattern formation.