Neural development: Patterning cascades in the neural tube

During vertebrate embryonic development, a portion of the ectoderm (outer layer) is set aside to make neural tissue. These cells initially form a ‘neural plate’, which later folds into a tube that will form the spinal cord and brain (Fig. 1). As the folding occurs, precursor cells in the neural plate are transformed into different neuronal subsets. Surrounding non-neural tissues initially polarize and pattern the neural plate and neural tube. A key feature of these initial events appears to be the establishment of polarizing centres within neural tissue itself.