(BQ) Part 2 book “Developmental neurobiology” has contents: Cell determination and early differentiation, neuronal survival and programmed cell death, synaptic formation and reorganization, and other contents. | Cell Determination and Early Differentiation 6 A wide range of cell types is needed to perform the many diverse functions of the adult nervous system. Each neuron, glial cell, sensory cell, and support cell must acquire highly specialized characteristics in order to contribute to the functions of the adult nervous system. The previous chapter discussed how vertebrate neuroepithelial cells divide, establish neural precursors, and migrate to new locations where they will ultimately differentiate into fully mature neurons. This chapter focuses on some of the common mechanisms by which cells of the invertebrate and vertebrate nervous systems transition from a precursor stage to acquire a particular cell fate. Processes regulating cell fate determination of subtypes of neurons, glial, and specialized sensory cells are considered. Cell fate is established over the course of development. During early embryogenesis, neuroepithelial cells have the potential to form numerous cell subtypes. As development progresses, however, cells are exposed to various signals that restrict their cell fate options. Depending on the specific precursor and the signals available, a given cell may remain multipotent—that is, retain the ability to develop into more than one cell type—for an extended period. However, this ability only persists up until the time of cellular determination, the stage at which further embryonic development or experimental manipulation can no longer alter the type of cell that forms. Thus, the determined cell has acquired its fate. A determined cell will then begin to differentiate and ultimately acquire the unique cellular characteristics associated with a particular cellular subtype. For some cell types, cell fate options become restricted early in the cell cycle in response to intrinsic cues, such as those that arise from nuclear or cytoplasmic signals inherited from a precursor cell. For other cells, fate is largely regulated by extrinsic cues encountered .
