Which feature forms the spinal cord and brain in chordates?

Which feature forms the spinal cord and brain in chordates?

• A. Notochord
• B. Gills
• C. Swim Bladder
• D. Dorsal Hollow Nerve Cord

Answer: (D)

In chordates, the central nervous system originates from the dorsal hollow nerve cord. This structure forms during embryonic development when the ectoderm thickens to become the neural plate, then folds inward to create the neural tube along the dorsal body axis. The anterior region of this tube develops into the brain, while the remaining portion becomes the spinal cord. The tube’s hollow interior will become the brain’s ventricles and the spinal cord’s central canal. The notochord provides axial support and sends developmental signals, but it does not become the brain or spinal cord. Gills and the swim bladder are unrelated to CNS formation, serving respiration and buoyancy purposes in various chordates.

In chordates, the central nervous system originates from the dorsal hollow nerve cord. This structure forms during embryonic development when the ectoderm thickens to become the neural plate, then folds inward to create the neural tube along the dorsal body axis. The anterior region of this tube develops into the brain, while the remaining portion becomes the spinal cord. The tube’s hollow interior will become the brain’s ventricles and the spinal cord’s central canal. The notochord provides axial support and sends developmental signals, but it does not become the brain or spinal cord. Gills and the swim bladder are unrelated to CNS formation, serving respiration and buoyancy purposes in various chordates.