What is the difference between the neural tube and the dorsal ventral cord?

Question

I was wondering what the difference is between the neural tube and the dorsal ventral cord.

I know that the neural tube forms during embryonic development from the ectoderm layer that folds inwards.
I thought that the neural tube gave rise to the central nervous system, however sometimes I see the following:

"the central nervous system develops from the hollow dorsal nerve cord"
for example: https://en.wikipedia.org/wiki/Dorsal_nerve_cord

question
What is the difference between the neural tube and the dorsal ventral cord or are they both the same? (talking about humans)

Answer 1

The terminology can be confusing, and I suspect the question you meant to ask was: what is the difference between the neural tube and dorsal nerve cord?

In vertebrates, the neural tube and the dorsal nerve cord are two names for the same structure. It develops into the brain and spinal cord.

Neurulation occurs during the early embryogenesis of chordates, and it results in the formation of the neural tube, a dorsal hollow nerve cord that constitutes the rudiment of the entire adult central nervous system.

_{Source: Colas J-F and Schoenwolf GC. Towards a cellular and molecular understanding of neurulation. Developmental Dynamics. 2001. vol 221(2): 117–145.}

This differs from invertebrates, some of which have a ventral nerve cord that does not invaginate and form a neural tube. As the name suggests, in contrast to vertebrates the nerve cord in these species is located ventrally.

In summary:
Dorsal nerve cord = neural tube
Ventral nerve cord ≠ neural tube

Answer 2

The neural tube (Fig. 1) is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord. Its structure can be described in standard anatomical terms of location and their respective axes.

The dorsal - ventral axis (back to abdominal side) can be visualized by dissecting the neural tube transversely (Fig. 2). This axis is important for development. In the spinal cord, for instance, the dorsal region is the place where the spinal neurons receive input from sensory neurons, while the ventral region is where the motor neurons reside. In the middle are numerous interneurons that relay information between them. The polarity of the neural tube is induced by signals coming from its immediate environment. The dorsal pattern is imposed by the epidermis, while the ventral pattern is induced by the notochord (Gilbert, 2000).

Conversely, the anterior - posterior axis (head to tail) can be seen by a longitudinal transection (Fig. 1). Here, the important regions of the brain can be identified; the neural tube balloons into three primary vesicles, namely the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon). The prosencephalon becomes subdivided into the anterior telencephalon and the more caudal diencephalon (Gilbert, 2000).

Hence, regarding your question - there exists no such thing as a dorsal ventral cord.

^{Fig. 1. Anterior-to-posterior axis of the neural tube. Early primary structures (left) and adult structures (right). source: Gilbert (2000)}.

^{Fig. 2. Dorsal-ventral axis of the neural tube. source: Gilbert (2000)}.

<sub>Reference
- Gilbert, Developmental Biology. 6^th ed. Sunderland (MA): Sinauer Associates (2000)</sub>