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Embryo test 5
| Question | Answer |
|---|---|
| what does the nervous systme develope from | the neural plate |
| formation of the nervous system is induced by ________ formation and ______ ______ | notochord (forms ventral to neural tube); paraxial mesoderm |
| what is neurulation | the proccess of formation of the neural plate, the neural folds, and their closure to form the neural tube |
| when is neurulation completed? | by the end of the fourth week, when closure of the caudal neuropore occurs |
| what is the embryo referred as in neurulation? | neurula |
| As the notochord develops, the embryonic ______ over it thickens to form te neural plate which is induced by the developing notochord | ectoderm |
| what does ectoderm (neuroectoderm) give rise to? | the central nervous system, consisting of the brain and spinal cord |
| where does thee neural plate first appear? | cranial to the primitive node and dorsal to the notochord process and the mesoderm adjacent to it |
| as the notochord forms and elongates what happens to the neural plate | it broadens and eventually extends cranially as far as the oropharyngeal membrane |
| when does the neural plate invaginate along its central axis to form a neural groove that has neural folds on each side? | 18th day |
| when doe the neural folds begin to move together and fuse, converting the neural plate into a neural tube? | end of 3rd week |
| what happens after the neural tube separates from the surface ectoderm? | the free edges of the surface ectoderm fuse so that this layer becomes continuous over the back of the embryo. Surface ectoderm differentiates into the epidermis of the skin |
| fusion of folds of the neural tube proceed in the ______ and ______ directions until only small areas remain open on both ends | cranial and caudal |
| when does the rostral neuropore close | 24 days |
| when does the posterior neuropore close | 2 days after the rostral neuropore (26 days) |
| what does the cranial two-thirds of neural plate develop into? | the brain |
| what does the caudal one-third of neural plate develop into? | spinal cord |
| before closure, the _______ of the neural tube- neural canal- communicates freely with amniotic cavity | lumen |
| closure of neuropores coincides with establishment of a ______ ______ _____ for neural tube | blood vascular circulation |
| the neural canal is converted into the _____ _____ of brain and ____ ____ ____ of spinal cord | ventricular system; central canal system |
| the sacral and coccygeal segments of the spinal cord (and corresponding dorsal and ventral roots) are formed by _______ _______ | secondary neurulation |
| secondary neurulation begins on day _____ and is completed by day ______ | 20; 42 |
| A cell mass called the ______ _______ appears caudal to the neural tube. It enlarges and cavitates and joins the neural tube | caudal eminence |
| as the neural folds fuse some neuroectodermal celly lying along the crest of each neural fold lose their epithelial affinities and attachments to neighboring cells. these cells are called what? | neural crest cells |
| As the neural tube separates from the surface ectoderm neural crest cells migrate _________ on each side of the neural tube | ventrolaterally |
| _____ _____ is formed by neural crest cells that form an irregular flattened mass between the neural tube and the overlying surface ectoderm | neural crest |
| the neural crest cells soon separates into right and left parts that migrate to the ___________ aspects of the brain and spinal cord | dorsolateral |
| separated neural crest cell's migratio to dorsolateral aspects of the brain and spinal cord give rise to what? | dorsal root gang, sympathetic gang, enteric gang, parasym gang of CN 7,9, and 10, schwann cells (myelinated PNS), satellite cells of peripeheral gang, cartilage of phary arches, ciliary & papillary musc, chromafin cells of adrenal medulla, & leptomeninges |
| what is Hirschprung disease (congenital megacolon)? | failure of neural crest to migrate and form enteric ganglia to lower bowel |
| what is Familial dystautonomia | problem with neural crest development and migration |
| what are the sensory symptoms of familial dystautonomia? | impaired pain and temperature perception |
| what are the motor symptoms of Familial dystautonomia | impaired autonomic symptoms (cardiovascular instability and gastrointestinal dysfunction) |
| what are placodes | specialized epidermal cells (head region) |
| placodes join neural crest to form sensory ganglia of which cranial nerves | 5, 7, 8, 9, and 10 |
| Olfactory placodes differentiate into _________ ______ that give rise to the olfactory nerve (CN 1) and induce the formation of ______ ________ | neurosensory cells; olfactory bulbs |
Created by:
jacquess17
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