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Neuroectoderm (or neural ectoderm or neural tube epithelium) consists of cells derived from the ectoderm. Formation of the neuroectoderm is the first step in the development of the nervous system . [ 1 ]
The neural tube develops in two ways: primary neurulation and secondary neurulation. Primary neurulation divides the ectoderm into three cell types: The internally located neural tube; The externally located epidermis; The neural crest cells, which develop in the region between the neural tube and epidermis but then migrate to new locations
Neuroepithelial cells of the ectoderm begin multiplying rapidly and fold in forming the neural plate, which invaginates during the fourth week of embryonic growth and forms the neural tube. [2] The formation of the neural tube polarizes the neuroepithelial cells by orienting the apical side of the cell to face inward, which later becomes the ...
Failure of neurulation, especially failure of closure of the neural tube are among the most common and disabling birth defects in humans, occurring in roughly 1 in every 500 live births. [42] Failure of the rostral end of the neural tube to close results in anencephaly, or lack of brain development, and is most often fatal. [43]
In vertebrate embryos, the ectoderm can be divided into two parts: the dorsal surface ectoderm also known as the external ectoderm, and the neural plate, which invaginates to form the neural tube and neural crest. [4] The surface ectoderm gives rise to most epithelial tissues, and the neural plate gives rise to most neural tissues.
Several layers such as the neural tube, neural crest, surface ectoderm, and mesoderm contribute to the development of the eye. [2] [3] [4] Eye development is initiated by the master control gene PAX6, a homeobox gene with known homologues in humans (aniridia), mice (small eye), and Drosophila (eyeless). The PAX6 gene locus is a transcription ...
They are found mainly in the olfactory epithelium, and as part of the retina. Multipolar: 1 axon and 2 or more dendrites Golgi I: neurons with long-projecting axonal processes; examples are pyramidal cells, Purkinje cells, and anterior horn cells; Golgi II: neurons whose axonal process projects locally; the best example is the granule cell
The communication between the neural plate and the notochord is important for the future induction and formation of the neural tube. Closure of the neural tube is completed when the neural folds are brought together, adhering to each other. While the cells that remain as the neural tube form the brain and spinal cord, the other cells that were ...