Axial Stem Cells and the Formation of the Vertebrate Body

Development of a whole multicellular complex organism from a single cell is not only an evolutionary triumph, but also the most daunting and formidable of tasks. The organism’s entire body plan is laid down in a series of intricate and interconnected events that comprise various levels of organization, from intracellular processes to vast morphogenetic tissue movements. This means that the embryo’s early symmetries must be gradually broken and that most of the initial cell potency needs to be progressively lost so that the body can increase in complexity and, ultimately, achieve its final form. In this chapter, using the mouse embryo as the chief model organism, we will address the formation of the vertebrate embryo from the perspective of the axial progenitor cells that are responsible for generating and patterning the tissues that will compose the postoccipital body structures.