Transverse section of half of a chick embryo of forty-five hours' incubation. The dorsal (back) surface of the embryo is towards the top of this page, while the ventral (front) surface is towards the bottom. (Neural tube is in green.)
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| colspan="2" |Chick embryo of thirty-three hours' incubation, viewed from the dorsal aspect (30x magnification).
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|Latin
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|
|colspan="2"|[subject #7 ]
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|System
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|Carnegie stage
|colspan="2"|[10]
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|Days
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|- class="hiddenStructure"
|Precursor
|colspan="2"|Neural groove
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|Gives rise to
|colspan="2"|Central nervous system (brain and spinal cord)
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|MeSH
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|Dorlands/Elsevier
|colspan="2"|[t_21/12827267]
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In the developing vertebrate nervous system, the neural tube is the precursor of the central nervous system, which comprises the brain and spinal cord. The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into a closed tube, the neural tube or canal, the ectodermal wall of which forms the rudiment of the nervous system.
There are two ways in which the neural tube develops: Primary neurulation and Secondary neurulation. In primary neurulation, the cells of the neural plate invaginate and pinch off to form the tube. In secondary neurulation, the cells of the neural plate form a cord-like structure that migrates inside the embryo and hollows to form the tube. Each organism uses primary and secondary neurulation to varying degrees. Neurulation in fish proceeds only via the secondary form, while in avian species the caudal regions of the tube develop using secondary neurulation and the anterior regions develop by primary neurulation. In mammals, a simmilar pattern is observed where secondary neurulation begins around the 35th somite.
The neural tube, for a short time is open both cranially and caudally. These openings, called neuropores, close during the fourth week in the human. Improper closure of the neuropores can result in neural tube defects such as anencephaly or spina bifida.
The dorsal part of the neural tube contains the alar plate, which is primarily associated with sensation. The ventral part of the neural tube contains the basal plate, which is primarily associated with motor (ie, muscle) control.
