A self-organizing embryoid model of peri-implantation human development
Project Summary The amniotic membrane forms a tough fluid-filled sac that protects the developing embryo and is essential for a successful pregnancy. Amniogenesis initiates early in human development as the embryo implants into the uterine wall: the inner cell mass first polarizes to form a pluripotent cyst with central lumen and subsequently, one half of this polarized cyst loses pluripotency markers and becomes squamous in nature (the prospective amniotic ecotderm) while the other side (the epiblast) remains pluripotent. Gastrulation begins on the epiblast side soon thereafter. These early post-implantation developmental steps are inaccessible to study in humans, leaving an enormous gap in our knowledge about amnion fate determination and formation of the amniotic sac, despite the central importance of these events to the survival of the developing embryo. A new in vitro model can help to close that gap: human pluripotent stem cells (hPSC), cultured in specific 3D conditions, form po