Making the Mouse Blastocyst: Past, Present, and Future

The study of the preimplantation mouse embryo has progressed over the past 50 years from descriptive biology through experimental embryology to molecular biology and genetics. Along the way, the molecular pathways that lead to the establishment of the three cell lineages of the blastocyst have become more clearly understood but the fundamental questions of lineage commitment remain the same as those laid out in early studies. With new tools of genome manipulation, in vivo imaging and single- cell analysis, the mouse blastocyst is an excellent model system to understand how organized cell fate decisions are made in a self- organizing developmental context.