In the developing chordate (including vertebrates), the neural tube is the embryonic precursor to the central nervous system, which is made up of the brain and spinal cord.

Four neural tube subdivisions each eventually develop into distinct regions of the central nervous system by the division of neuroepithelial cells: the forebrain (prosencephalon), the midbrain (mesencephalon), the hindbrain (rhombencephalon) and the spinal cord.

Improper closure of the neuropores can result in neural tube defects such as anencephaly or spina bifida.

[3] According to the French flag model of morphogenesis, this patterning occurs early in development and results from the activity of several secreted signaling molecules.

The different combinations of expression of these transcription factors along the dorsal-ventral axis of the neural tube are responsible for creating the identity of the neuronal progenitor cells.

Also, the position at which these neuronal groups are generated in vivo can be predicted by the concentration of Shh required for their induction in vitro.

Researchers observed changes in dorsal-ventral patterning, for example, zebrafish deficient in certain BMPs showed a loss of dorsal sensory neurons and an expansion of interneurons.