The dorsal nerve cord is located dorsal to the notochord and thus also to the gut tube (hence the name). It is formed from clustered neuronal differentiation at the axial region of the ectoderm, known as the neural plate.

2024年11月23日 · The dorsal hollow nerve cord derives from ectoderm that rolls into a hollow tube during development. In chordates, it is located dorsally (at the top of the animal) to the notochord. In contrast to the chordates, other animal phyla are characterized by solid nerve cords that are located either ventrally or laterally.

Animals in the phylum Chordata share five key characteristics that appear at some stage during their development: a notochord, a dorsal hollow (tubular) nerve cord, pharyngeal gill arches or slits, a post-anal tail, and an endostyle/thyroid gland (Figure 29.3).

In most invertebrate phyla, the nerve cord is ventral to the alimentary canal and solid. In chordates, the single cord is dorsal to the alimentary canal and is tubular. The anterior end enlarges to form the brain. The cord is produced by the infolding of ectodermal cells on the dorsal side of the body.

All chordates are deuterostomes possessing a notochord. Animals in the phylum Chordata share five key chacteristics that appear at some stage during their development: a notochord, a dorsal hollow (tubular) nerve cord, pharyngeal gill arches or slits, a post-anal tail, and an endostyle/thyroid gland (Figure 2).

In chordates, four common features appear at some point during development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail. The endostyle is embedded in the floor of the pharynx.

With increasing muscle-based locomotion, the dorsal nerve cord took over innervative control of locomotion, freeing the epidermal nerve cells for other functions.