The document summarizes the development of the spinal cord. It describes how the neural tube forms from neuroepithelial cells. The neuroepithelial cells then proliferate and form layers, including the mantle layer which contains neuroblasts and forms the grey matter, and the marginal layer containing nerve fibers which forms the white matter. It further discusses the formation of basal, alar and roof plates, and how neuroblasts in different regions form motor and sensory areas. Glial cells including astrocytes and oligodendrocytes also develop from neuroepithelial cells to support neurons.