Neural Induction Embryonic Stem Cells

An early milestone in the development of the vertebrate central nervous system (CNS) occurs soon after gastrulation when the neural plate forms on the dorsal surface of the embryo. Appearance of the neural plate marks the generation of committed neural progenitors that proliferate and eventually gives rise to the cell types comprising the CNS. The importance of determining how a particular region of the embryo forms the neural plate led to the discovery of neural induction in the early part of the last century. We will first describe how the process of embryonic induction was defined experimentally, how the mechanisms involved are evolutionarily conserved, and how the molecular circuitry that underlies this process was unraveled more recently. In addition, as the neural plate forms, the cells within it are molecularly distinct according to their position along the body axis. Regionalization of the neural plate is the first step in neural patterning, the events that allow progenitors to form different types of neural tissue along the body axis. We describe how regionalization of the nervous system begins at the neural plate stage, focusing on how polarity along the anteroposterior axis is first established. Finally, understanding the mechanisms that allow neural tissue to form in the embryo and become regionalized has been influential in more recent attempts to guide the differentiation of embryonic stem cells (ESCs) in culture. We will describe how the mechanisms that determine early cell fate in embryos have been used to devise protocols for guiding ESC differentiation.