The neural tube comprises of a bundle of nerve sheaths and is the embryonic structure that ultimately forms the primitive brain at the cranial end and the spinal cord at the caudal end .
The neural tube is formed during an embryological process called neurulation, a folding process where the neural plate transforms into the neural tube . The center of the tube is the neural canal . Neurulation starts at approximately day 20 after fertilisation and is completely closed by approximately day 29 .
There are distinct vesicles which make up the neural tube . Each of these subdivisions develops into distinct regions of the central nervous system, resulting in brain development :
- prosencephalon (forebrain)
- mesencephalon (midbrain)
- rhombencephalon (hindbrain)
- spinal cord
When the primary vesicles of the brain are formed, they can be recognized with endovaginal sonography.
Failure of neural tube closure in early pregnancy can result in neural tube defects, one of the commonest and most severe malformations of the fetus and newborn .