Specification and Maintenance of Cell Identities in the Early Mammalian Embryo

A unique paradigm for the analysis of cell fate decisions in vivowith high spatiotemporal resolution in mammals is the preimplantationmouse embryo. We are focusing our research on theformation of pluripotent epiblast (Epi) and extra-embryonicprimitive endoderm (PrE) cell lineages within the inner cellsof the blastocyst. Initially, uncommitted inner cells co-expressmarkers of both lineages. Epi and PrE are then asynchronouslyspecified within the inner cell mass of the blastocyst in a saltand pepper pattern and become spatially segregated before theimplantation. We are investigating the contributions of candidatefactors and regulatory mechanisms using both pharmacologicaland genetic perturbations on mouse embryos combinedwith ۳D live imaging and lineage specific fluorescent reporters.I will present our recent data on the temporal dynamics of Epiand PrE progenitor emergence and the mechanisms controllingprogenitors maintenance after their specification.