One of the most striking features of embryonic development is that differentiation is happening in a spatially ordered fashion: tissue self-organize to form well-defined patterns that pre-figure the body plan. During gastrulation, the cells of the embryo are allocated into three germ layers: ectoderm, mesoderm and endoderm. During the last decades, signaling pathways responsible for the initiation of gastrulation in mammalian embryos have been identified. However, the physical rules governing the tissue spatial patterning and the extensive morphogenetic movements occurring during that process are still elusive.

Studying the spatio-temporal dynamics of pattern formation is difficult in live embryos, because of their inherent lack of observability but also because it is not possible in an embryo to control in a quantitative manner what is relevant for the establishment of the multi cellular pattern, ie. the cells’ physical and chemical environment.

I will discuss how culture and differentiation of mouse and human Embronic Stem Cells on micro-patterned substrates allowed us to recapitulate some aspects of Antero/Posterior axis formation occurring at gastrulation and how microfluidic devices can help us dissect the emergence of A/P polarity.