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30 Cards in this Set
- Front
- Back
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From what germ layer does the NS arise?
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Ectoderm
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What is the default state of ectodermal cells?
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Neuronal Tissue - but release factors telling neighbors NOT to be N.S.
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How does Neural tube form?
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See notes
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What are the 4 neural tube closure defects?
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1. Spina Bifida
2. Meroanencephaly 3. Anencephaly 4. Exencephaly |
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What is a defect in the vertebral arch formation or neural tube closure resulting in an exposure and possibly extrusion of the spinal cord and its surrounding tissues?
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Spina Bifida
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What is a defect in cranial neural-tube closure that results in partial absence of the brain
Most common tube defect |
Meroanencephaly
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What is a defect in cranial neural tube closure that results in complete absence of brain?
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Anencephaly
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What is a defect in cranial neural tube closure that results in exposure and possibly extrusion of brain?
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exencephaly
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What are the 3 vesicles seen in the broad cranial end of the neural plate at week 4?
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1. Forebrain
2. Midbrain 3. Hindbrain |
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What are the 5 vesicles seen in week 5?
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Telencephalon, Diencephalon (forebrain)
Mesencephal (Midbrain) Metencephalon, Myelencephalon (hindbrain) |
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What are the 9 special subdivisions of the hindbrain called?
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Rhombomeres
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What is the purpose of hox genes?
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Specify segmental identity along the Anterior/Posterior axis
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What defines specific rhombomere segmental identify?
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A combinatorial Hox code - giving different TF's
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What important nerves emerge from specific rhombomeres?
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Cranial nerves (except CN I - IV??)
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Generally, what patterns the dorso-ventral axis in the neural tube?
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Localized inductive cues
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What is the role of floor plate in D-V patterning?
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Secretes signals to instuct VENTRAL cells to acquire specific fates:
Sonic Hedgehog (SHH) |
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What is the role of roof plate in D-V patterning?
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Secretes other signals to instruct DORSAL cell fates
Bone Morphogenic Proteins (BMPs) |
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What does the notochord induce?
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The floor plate
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How, cellularly, does SHH help pattern the NT?
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Different concentrations of SHH induce different TF's
Specific pairs of TF's determine cell fate |
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What is a defect in the bifurcation of the forebrain, resulting in a single hemisphere?
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Holoprosencephaly
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What is one main cause of holoprosenchephaly?
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Loss of SHH signaling
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What is neural crest cell fate largely determined by?
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LOCATION (therefore can transplant them) that gives different external cues
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How do neurons assume specific identities?
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Different combination of signals, presumably similar to those present at particular locations in embryo, induce different cell fates
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How are the cortical layers developed?
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INSIDE-OUT maturation
- new neurons migrate past older layers |
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How do axons find their appropriate targets?
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Guidance Cues that are differentially localized
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What is it called when a patient can't look side to side?
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Horizontal gaze palsy
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What is horizontal gaze palsy caused by?
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Disruption of robo-3 gene
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What are a family of extracellular signaling molecules that promote the survival of specific neurons?
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Neurotrophins
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How does cell survival depend on target aquisition?
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Post-synaptic cells (target) secretes TROPHIC FACTORS that are required for neuronal survival
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What happens to neurons that do not receive enough Neurotrophic Factors?
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They die via apoptosis
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