Implicating stem cell identity in embryonic morphogenesis

During mammalian development, complex transcriptional networks drive cell fate specification events and tissue - scale reorganizations to form different cell and tissue types . The first morphogenetic reorganization of the embryonic stem cells, known as epiblast, takes place at the time of embryo implantation into the uterus . However, our knowledge of mammalian development at implantation is very scarce due to technical and ethical limitations . To overcome these hurdles, we have recently established an in vitro culture method that allows human embryos to develop beyond implantation in vitro . Moreover, we can mimic critical early post - implantation events using 3 D cultures of stem cells . These novel methods represent ideal experimental models to decipher the complex interplay stem cell identity and embryonic morphogenesis . For example, we have recently identified that a pluripotent - state transition directs the transformation of the mouse and human epiblast into an epithelial tissue . Our results provide the first molecular link between the pluripotency network and the 3 D tissue architecture, and exemplify the complex interplay between different scales of organization . The developmental arrest of mouse and human embryos upon deregulation of the pluripotency network supports the physiological relevance of our findings .