An article published in Nature shows that during the development of the preimplantation embryo, the establishment of apicobasal cell polarity is fundamental for the transition from totipotency to pluripotency of cells in that embryo, which induces cell differentiation towards the trophectoderm. In mice (read HERE), this occurs in the eight-cell embryo and is regulated by a “molecular clock”, which is independent of the size of the embryo and its development. However, the mechanisms that govern these changes are virtually unknown.

Now, the team led by Magdalena Zernicka-Goetz has identified some molecules that are necessary and sufficient to trigger cell polarization in mouse embryos by identifying three factors that are required for the polarization process: Tfa2c, Tead4, and RhoA (see more HERE).