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28 Cards in this Set
- Front
- Back
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when does gastrulation begin? what layer does the notochord form from?
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- 3rd week (formation of 3 layers)
- forms from mesoderm |
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how does neural induction occur?
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- ectoderm overlying notochord transformed into neural plate (called the neuroectoderm)
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what are neurocutaneous disorders?
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- disorders involving CNS & skin (because they both come from ectoderm)
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what 3 structures does the neuroectoderm progress through?
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- neural plate --> neural groove --> neural tube
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During what days does the neural tube start to close? what happens to it at head vs tail?
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- 3-4 weeks (22 days)
- expands into ventricles at the head, atrophies into canal of spinal cord at tail |
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what days do the anterior & posterior neuropores close?
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- anterior at day 25 (ventricles of brain)
- posterior at day 28 (spinal cord) |
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what is it called when the posterior neural cord does not close?
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- spina bifida
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what is spina bifida occulta?
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- failure of bones to form
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what is a meningocele?
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- just meninges & spinal fluid sticking out
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what is a myelomeningocele?
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- see nerve roots/spinal cord, meninges & fluid
- compromises nerve supply to legs & bladder |
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what is encephalocele?
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- anterior cord closure failure
- meninges & sometimes brain herniated through defect in skull & scalp |
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what is tethered cord syndrome?
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- disorder where conus medlars & filum terminale abnormally stuck to vertebral column
- with growth of cord this compromises it's function |
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what is anencephaly?
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- failure of brain to form (infant can survive because of brainstem function)
- failure of anterior cord to develop at all |
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where are neural crest cells with regards to the neural groove?
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- neural crest cells are at the very top of the groove
- start at ridge & migrate down side of groove |
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what do the neural crest cells give rise to?
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- bones of lower skull
- meninges (pia + arachnoid = leptomeninges) - schwann cells - sensory ganglia - sympathetic neurons - parasympathetic (VIII, IX, X) - enteric neurons |
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what does the prosencephalon become? mesencephalon? rhombencephalon?
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- prosencephalon: telencephalon & diencephalon (thalamus, hypothalamus, optic vesicle, retina)
- mesencephalon: midbrain - rhombencephalon --> metencephalon: pons + cerebellum & myencephalon: medulla |
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what two cells types come from ectoderm? how do you further subdivide macroglia?
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- neuroblasts --> neurons
- glioblasts --> macroglia (oligodendrocytes, astrocytes, radial glial cells --> ependymal cells) |
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where do microglia originate from?
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- mesoderm (from circulating monocytes)
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how do radial glial cells work?
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- neurons born in the germinal matrix (right next to lateral ventricles) --> migrate out via radial glial cells --> once radial glial cell life is over they differentiate into ependymal cells or astrocytes
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where are neurons born?
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- germinal matrix
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what are the 5 layers of concentric zones of neural tube?
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- ependymal layer (ventricular zone w/ ependymal cells & subventricular zone w/ germinal matrix & neuroblasts)
- mantle layer (intermediate zone) - marginal layer (marginal zone & cortical zone) |
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what are the two brain growth spurts?
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- 10-18 weeks = vulnerable to infections & irradiation
- 30th week - 2 years = vulnerable to malnutrition & environment |
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what do you worry about with the germinal matrix in pre-mature babies?
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- the germinal matrix is still developing so you're susceptible to changes in BP & homeostasis
- worry about HEMORRHAGE in germinal matrix |
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what are the phases of neuronal maturation?
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- elongation of axons --> dendrite formation --> expression of biochemical markers --> formation of synapses
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what is agenesis of the corpus callosum?
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- major pathway connecting left & right hemisphere
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what is the difference between the floor & roof plate of the neural tube?
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- roof plate: dorsal of spinal cord = sensory (uses BMP & dorsalin)
- floor plate: ventral = motor (sonic hedgehog = SHH, Noggin, chordin) |
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what are some important genes in rostral-caudal patterning?
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- homeobox, homeotic, HOX genes
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how does cellular polarity play a role in spinal cord? what happens if there is a problem with cilia?
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- ependymal cells have cilia - essential for CSF flow (dyslexia controls cilia cell migration)
- if there is a problem with cilia you might end up with non-obstructive hydrocephalus |
