Updates on preimplantation embryo research.

Preimplantation development is the only stage of human development that can be studied outside the body in real time, as human embryos can be produced by in vitro fertilization and cultured in the laboratory as self-contained structures until the blastocyst stage. Here, we focus some of the key cellular and morphogenetic processes by which the 1-cell embryo is transformed gradually into a blastocyst ready for implantation. Although most of our knowledge about the dynamic series of events patterning preimplantation human development derives from work in mouse embryos, we discuss key differences that could exist with humans. Furthermore, we highlight how new approaches may enable to reveal many of the unknown processes driving human preimplantation development, particularly using noninvasive imaging and genetic technologies.