Neuronal specification in the spinal cord: Inductive signals and transcriptional codes

Neural circuits are assembled with remarkable precision during embryonic de velopment, and the selectivity inherent in their formation helps to define the behavioural repertoire of the mature organism. in the vertebrate centra l nervous system, this developmental program begins with the differentiatio n of distinct classes of neurons from progenitor cells located at defined p ositions within the neural tube. The mechanisms that specify the identity o f neural cells have been examined in many regions of the nervous system and reveal a high degree of conservation in the specification of cell fate by key signalling molecules.