View on Brain

Human brain development is a protracted process that begins in the third gestational week (GW) with
the differentiation of the neural progenitor cells and extends at least through late adolescence,
arguably throughout the lifespan. In humans the embryonic period begins at conception and extends
through gestational week 8 (GW8). By the end of the third week, the embryo is transformed through a
set of processes that are referred to collectively as gastrulation into a three-layered structure. The
transformation of cell lines that occur during gastrulation set the stage for all subsequent
developments in the embryo. Among the stem cell lines that emerge during gastrulation are the neural
stem cells. The neural stem cells are capable of producing all of the different cells that make up the
brain and central nervous system (CNS), and for this reason the neural stem cells are usually called
the neural progenitor cells. At the end of gastrulation the cells located along the midline of the upper
layer of the embryo have transformed into neural progenitor cells. The neuroectodermal stem cells are
the neural progenitor cells that will give rise to the brain and central nervous system (CNS).