as part of embryonic development the neural tube will become the central nervous system.
as part of embryonic development the neural tube will become the central nervous system.
as part of embryonic development the neural tube will become the?
central nervous system
the mammalian central nervous system (cns) is derived from the ectoderm—the outermost tissue layer of the embryo. in the third week of human embryonic development the neuroectoderm appears and forms the neural plate along the dorsal side of the embryo. the neural plate is the source of the majority of neurons and glial cells of the cns. a groove forms along the long axis of the neural plate and, by week four of development, the neural plate wraps in on itself to give rise to the neural tube, which is filled with cerebrospinal fluid (csf). as the embryo develops, the anterior part of the neural tube forms three brain vesicles, which become the primary anatomical regions of the brain: the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon). these simple, early vesicles enlarge and further divide into the telencephalon (future cerebral cortex and basal ganglia), diencephalon (future thalamus and hypothalamus), mesencephalon (future colliculi), metencephalon (future pons and cerebellum), and myelencephalon (future medulla). the csf-filled central chamber is continuous from the telencephalon to the spinal cord, and constitutes the developing ventricular system of the cns. because the neural tube gives rise to the brain and spinal cord any mutations at this stage in development can lead to fatal deformities like anencephaly or lifelong disabilities like spina bifida. during this time, the walls of the neural tube contain neural stem cells, which drive brain growth as they divide many times. gradually some of the cells stop dividing and differentiate into neurons and glial cells, which are the main cellular components of the cns. the newly generated neurons migrate to different parts of the developing brain to self-organize into different brain structures. once the neurons have reached their regional positions, they extend axons and dendrites, which allow them to communicate with other neurons via synapses. synaptic communication between neurons leads to the establishment of functional neural circuits that mediate sensory and motor processing, and underlie behavior.
development of the nervous system
in front of the primitive streak, two longitudinal ridges, caused by a folding up of the ectoderm, make their appearance, one on either side of the middle line formed by the streak. these are named the neural folds; they commence some little distance behind the anterior end of the embryonic disk, where they are continuous with each other, and from there gradually extend backward, one on either side of the anterior end of the primitive streak. between these folds is a shallow median groove, the neural groove. the 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. after the coalescence of the neural folds over the anterior end of the primitive streak, the blastopore no longer opens on the surface but into the closed canal of the neural tube, and thus a transitory communication, the neurenteric canal, is established between the neural tube and the primitive digestive tube. the coalescence of the neural folds occurs first in the region of the hind brain, and from there extends forward and backward; toward the end of the third week, the front opening (anterior neuropore) of the tube finally closes at the anterior end of the future brain, and forms a recess that is in contact, for a time, with the overlying ectoderm; the hinder part of the neural groove presents for a time a rhomboidal shape, and to this expanded portion the term sinus rhomboidalis has been applied. before the neural groove is closed, a ridge of ectodermal cells appears along the prominent margin of each neural fold; this is termed the neural crest or ganglion ridge, and from it the spinal and cranial nerve ganglia and the ganglia of the sympathetic nervous system are developed. by the upward growth of the mesoderm, the neural tube is ultimately separated from the overlying ectoderm.
embryonic development