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The Mysterious Neural Tube Formation: Why Is Embryonic Development So Important?
In the early stages of vertebrate embryonic development, the formation of the neural tube is a critical and mysterious process. This process is called neurulation and involves the folding of the neural plate into a neural tube. The embryo at this stage is called a neurula. The development of the neural tube is critical to the formation of the central nervous system (CNS), with subsequent development of the spinal cord and brain.
The process of neurulation begins with the induction of the notochord, which causes the overlying ectoderm to form a thick, flat neural plate.
During this process, the ectoderm, promoted by signals from the notochord, begins to thicken and flatten, forming the neural plate. The cells of the neural plate gradually fold to form the neural tube, which eventually differentiates into the spinal cord and brain. Studies have shown that cell pinching and differential proliferation are sufficient for mammalian neurogenesis, suggesting that specific cell biology mechanisms drive neural tube formation.
Exploration of the primary neurogenesis process
In primary neurogenesis, the earliest induction concept was proposed by Pador in 1817, and was subsequently experimentally verified by Viktor Hamburger, Hans Spemann and others. Spellman used his student Hilda Mangold to conduct famous experiments to demonstrate that certain regions of the ectoderm could induce the formation of neural tissue. Mangold's experiments demonstrated the possibility of induction by transplanting dorsal lip tissue from a developing salamander embryo into another embryo.
Induction is a complex and extensive process. With the continuous research of scientists in the 20th century, more and more unexpected substances have been discovered to have induction functions.
In studies of developmental biology, many chemically induced factors, including growth factors and other proteins, have been found to be involved in the formation of the neural plate. These studies undoubtedly advance our understanding of neurogenesis, although there are still many uncharted territories waiting to be explored in this process.
Shape changes and folding process of neural plate
As neurulation progresses, the cells of the neural plate undergo significant shape changes, becoming tall columnar and exhibiting a characteristic arrangement. The cells move sideways, forming a truncated pyramid shape, a dynamic process of small changes. This shape change further promotes the folding of the neural plate into the neural tube, forming the structures of neural grooves and neural folds.
Eventually, the neural creases merge with each other at the midline, a process that requires tight regulation by cell adhesion molecules.
The folding process of the neural plate begins at approximately the level of the four somites and ultimately forms the complete neural tube. This series of changes reveals the complex mechanism of neural tube closure, and its failure may lead to congenital neural tube defects and impair the function of the central nervous system.
Patterning and development of the neural tube
During neural tube development, specific gene product gradients are critical for patterning of the neural plate. These genes, such as Hox genes, Emx genes and Wnt signaling factors, all play an indispensable role in the formation of the neural tube. These genes influence the formation of structures that regulate the development from the neural plate to the neural tube, allowing the major parts of the forebrain, midbrain, and hindbrain to develop smoothly.
Abnormal closure of the neural tube is considered one of the most common and disabling birth defects in humans.
Neural tube defects such as anencephaly and spina bifida are important clinical phenomena caused by failure of neural tube closure. These problems not only affect the quality of life of patients, but also cause a significant burden on society and medical resources. Therefore, an in-depth understanding of the formation process of the neural tube is not only of great significance to basic scientific research, but also crucial to the prevention and treatment of related diseases.
Epilogue
With the advancement of science and technology, the understanding of the process of neural tube formation is becoming clearer. However, many questions still need to be answered. For example, how do cells cooperate with each other during each step of neural tube closure to promote correct development?
