Abstract

The events at the time the mammalian embryo implants have been largely hidden from us – they take pace as embryos embed into the maternal tissues. To overcome this difficulty we have developed a culture system for embryos to permit their development at this stage outside the body of the mother and allows us to observe these events by time-lapse microscopy. This has revealed the first steps in how the pluripotent epiblast cells organise themselves into a structure that will develop into the foundation for the body. This requires cells to respond to signals from underlying basal membrane. Remarkably we can mimic this with a gel of extracellular matrix proteins and get ES cells to undertake the same self-organisation process. Just as a baby needs help to walk, so the epiblast needs the assistance of the flanking extra-embryonic tissues to guide its development and specify the body axes. Now we wish to understand precisely how these tissues interact to set the embryo on its correct developmental course.