The vertebrate nervous system consists of the central nervous system (brain, spinal cord, and retina) and the peripheral nervous system (sensory neurons, nerves, and ganglia). During embryonic development, dorsal mesoderm cells produce growth factors that specify neural cell fate in the ectoderm. For instance, early studies showed that inhibition of BMP and activation of FGF signaling pathways are necessary for neural induction. After specification, the process of neurulation forms the neural tube, which gives rise to the central nervous system. Neurulation also establishes two ectodermally-derived strips of cells above the neural tube called the neural crest. Neural crest cells migrate away from the neural tube and give rise to the peripheral nervous system and other specialized cell types. Later stages of nervous system development include neural stem cell differentiation into neurons and glial cells, neuron migration, axon outgrowth, and synapse formation and remodeling.