The dorsal hollow nerve cord forms which major nervous system component?

• A. Spinal cord
• B. Brain
• C. Peripheral nerves
• D. Enteric nervous system

Answer: (A)

The dorsal hollow nerve cord is the embryo’s neural tube, which becomes the central nervous system. As development proceeds, the front (rostral) part enlarges to form the brain, while the back (caudal) part curves and thickens to form the spinal cord. So from this structure, you get the core components of the CNS, including both brain and spinal cord. Among the given options, the spinal cord is the best single representative derivative because it directly emerges from the posterior neural tube and is a major, clear product of this structure. The brain does form as well, but the question points to the spinal cord as the primary CNS structure arising from the dorsal hollow nerve cord. Peripheral nerves and the enteric nervous system arise mainly from neural crest cells and other tissues, not directly from the dorsal nerve cord.