Our studies investigate the function of gene families that coordinate trophectoderm differentiation (the first epithelium) and blastocyst formation, and have included growth factors; growth factor binding proteins; anti-oxidant enzymes; cell adhesion molecules; tight-junction associated polypeptides; Na/K-ATPase isoforms; aquaporin water channels (AQPs); and most recently RhoGTPases and p38 MAPK signalling pathway members. Our research investigates these events during both mouse and cow preimplantation development. Both of these species are important models for human early development.