What Is the Neural Tube?

The neural tube is the origin of the central nervous system and is closed by the neural groove. The head of the neural tube first appeared three spherical swells, that is, three brain vesicles, anterior, middle and rhombic. The forebrain is differentiated into the telencephalon and the mesobrain, the midbrain is differentiated into the midbrain, and the rhizome is differentiated into the hindbrain and endbrain. The telencephalon further develops into two cerebral hemispheres, the hindbrain develops into a pontine and cerebellum, and the last brain develops into the medulla oblongata.

The neural tube is the origin of the central nervous system and is closed by the neural groove. The head of the neural tube first appeared three spherical swells, that is, three brain vesicles, anterior, middle and rhombic. The forebrain is differentiated into the telencephalon and the mesobrain, the midbrain is differentiated into the midbrain, and the rhizome is differentiated into the hindbrain and endbrain. The telencephalon further develops into two cerebral hemispheres, the hindbrain develops into a pontine and cerebellum, and the last brain develops into the medulla oblongata.

Nervous system The primitive structure of the nervous system in the central part of the embryo. This tube is gradually closed and healed into a hollow neural tube from the two nerve folds at the end of the 4th week of the embryo. If the front end of this neural tube is incompletely closed, children may form congenital cranial fractures and may be accompanied by other deformities; if the rear end is incompletely closed, congenital spina bifida may be formed, which will have serious consequences for the sick child.

Chinese name

Neural tube

Foreign name

neuraltube

For object

Vertebrates and Protozoans

Way of forming

Both

Neural tube anatomy

The neural tube is the main primordium of the nervous system. At the end of the 3rd week, the dorsal ectodermal cells rapidly thickened and widened under the induction of the chordae. Soon, nerve folds formed on both sides of the nerve. The central folds of the two folds form a neural groove. The neural sulcus continued to deepen. At the end of the 4th week of the embryo, the nerve folds on both sides gradually closed and healed into a hollow neural tube, separated from the ectoderm and buried in human mesoderm tissue. The front of the neural tube develops into the brain and the back develops into the spinal cord.

Neural tube defects and their causes

Neural tube defects usually refer to birth defects that occur in the central nervous system. Nervous tissue is often exposed. Such as cranial spina bifida, the entire nervous system is exposed; in addition, there are no brain deformities, spinal meningocele, cerebral bulge, and so on.

A large number of studies have shown that neural tube defects are related to many factors, and it is suggested that external environmental factors are closely related to the increased risk of neural tube defects, such as geographical location, month of conception, epidemic trend, mother's diet, mother's disease, and medication. For example, the incidence of neural tube defects is highest in northwestern Britain and lowest in the southeast. A similar situation occurs in the United States. Seasonal changes also affect the occurrence of neural tube defects. Starting pregnancy in Great Britain in March, April, and May seems to have a higher risk. In Canada, pregnancy in September and October appears to cause the highest incidence of neural tube defects. Maternal age and parity also affect neural tube defects, and most studies have shown that people with neural tube defects are found in children older than the first child. Most defective children are born when the mother is younger than 20 or older than 35.

Socioeconomic conditions also affect the occurrence of neural tube defects. Much research has been done on the relationship between diet and neural tube defects, with recent attention being paid to studies of zinc and folic acid. Zinc deficiency can increase the risk of birth defects in offspring, and human studies have yet to draw conclusions. It has been found that infants with neural tube defects have low serum zinc, while other studies have found increased levels of zinc in umbilical cord blood in defective newborns. Folate antagonists are known to cause neural tube defects. Supplementation of folic acid and multivitamins to high-risk mothers resulted in a lower than expected number of birth defects in offspring. A mother's illness in the first month of pregnancy can be a contributing factor to certain neural tube defects. Babies born to mothers with diabetes are 3 to 21 times more likely to develop neural tube defects than control babies. Maternal exposure to high temperatures during the first month of pregnancy is also associated with neural tube defects. The drug has an effect on neural tube defects, but it has only been reported in individual cases. Occupational exposure to industrial chemicals before or during the first trimester of pregnancy is also related to birth defects in children, including neural tube defects. Much research is needed today to confirm it. The mother's heavy drinking in the first month of pregnancy is related to the occurrence of infant neural tube defects. Genetic factors also affect neural tube defects. For example, the incidence of neural tube defects is high in the two ethnic minorities in the United States. Gender differences are more pronounced in anencephaly and spinal meningoceles, and the cause is unknown.

Neural tube and neural tube related diseases

Neural tube malformations:

A group of common neonatal congenital malformations, most of them with or without brain, spina bifida and so on. The former is severe brain dysplasia with skull defects. Such children can only survive for a few days after birth, at most not more than a few weeks; children with spina bifida can live longer, about several years, but often with meningocele Sometimes the cause of hydrocephalus and neural tube defects is unclear. A large number of epidemiological investigations and other evidence show that environmental factors play an important role. The relationship between low folate levels in pregnant women and this disease has become the current research focus.

The congenital defect caused by the failure to close the neural tube when the embryo develops in the mother to the 3rd to 4th week. Mainly include abnormalities in the development of the central nervous system such as spina bifida and anencephaly. Anencephaly is a severe brain hypoplasia and a skull defect. It usually dies before or shortly after birth. Although children with spina bifida can survive, they become permanently disabled. Folic acid deficiency in the first trimester is the main cause of neural tube defects. Adding folic acid in time before pregnancy to early pregnancy can effectively prevent neural tube defects.

The process of neural tube closure is complicated, and the frequency of mutations in different genes and their degree of influence on genetic susceptibility are not the same. Therefore, neural tube defects are manifested in various clinical characteristics and different degrees of incidence. Only by fully understanding the pathogenesis of neural tube defects, avoiding the influence of harmful environmental factors, and taking corresponding measures to prevent and control according to the pathogenesis, can the incidence of neural tube defects be effectively reduced.