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32 Cards in this Set
- Front
- Back
When does the neural ectoderm form the neural plate?
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In the early embryo (~18 days)
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When does the neural tube become internal
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~4 weeks
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From whence the the ventricular system and central canal of the spinal cord
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The cavity of the neural tube
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What are the four concentric zones of the neural tube
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the ventricular & subventricular, mantle, and marginal zones or layers
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from whence the neurons
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neuroblasts in the ventricular zone of the neural tube
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from whence ependymal cells
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spongioblasts of the ventricular zone of the neural tube
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from whence macroglia
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glioblasts of the ventricular zone of the neural tube
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when is the most rapid phase of neuronal mitotic activity
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from 12-20 wks of gestation, the first critical period of brain development
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From whence the mantle layer
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from migrating primitive neurons generated in the ventricular zones
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The marginal layer becomese
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the white matter of the mature CNS
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Areas where neural tube has not fused by 4 weeks
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anterior neuropore, rhomboid fossa, posterior neuropore
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rhomboid fossa becomes what
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the 4th ventricle of the mature brain
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what are the three vesicles or dilations or the developing brain
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the prosencephalon (forebrain), the mesencephalon (midbrain), and the rhombencephalon (hindbrain)
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Prosencephalon becomes
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telencephalon and diencephalons
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when is the second critical period of brain development?
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third trimester of gestation through about 2 yrs. of age
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first part of commissural system in development
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lamina terminalis
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embryonic Mesencephalon becomes:
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midbrain
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Rhombencephalon becomes:
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metencephalon and myelencephalon
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Rhomboid fossa Ventricular zone becomes:
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cerebellar plate (analogous to the cortical plate)
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mantle layer of the cerebellar plate will differentiate into
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neurons of deep cerebellar nuclei, Purkinje cells, and Golgi cells
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Cells located at the rhombic lip; a small group of specialized somatic sensory neurons (General Somatic Afferents; GSA) which give rise to an external granular layer which develops on the outside of the cerebellar cortex with cells which will differentiate into…?
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granule, basket, and stellate cells in the mature cerebellum; granule cells will migrate so that in the adult brain they come to occupy the deepest layer of the cerebellar cortex (the granule cell layer);
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Neurons generated from the rhombic lip are also thought to migrate into the brainstem to become…
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the pontine nuclei and the inferior olive
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Medulloblastomas definintion
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malignant embryonal tumors of the cerebellum with a tendency to metastasize; constitute ~20% of pediatric CNS neoplasms with a peak incidence at 3-8 yrs; occur with greater frequency in males
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from whence the choroids plexus
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At two areas of the developing nervous system where the neural tube does not fuse, the pia (the innermost meningeal layer) and ependymal cells interact; Lateral ventricle; the major site of CSF production in the CNS, & 4th ventricle
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define Encephalocele (“pouch”)
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failure of fusion above the spinal cord, most commonly the dorsal and occipital area; no bone forms and a pouch of brain tissue extrudes from the skull
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Hydranencephaly:
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the two cerebral hemispheres form, but then a regression of the tissue occurs, and the cavity fills with CSF; can be due to maternal trauma, or to vascular problems in the fetal brain
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Porencephaly
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failure of the normal migration of neurons in the telencephalon to form the normal C-shaped configuration of the hemispheres
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in humans neural plate formation begins when?
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day 18
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deep neural groove has formed by what day
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20
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neural tube closure begins at what day, begins where in tube
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day 20/21, starts in middle of tube
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cranial neuropore closes what day
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24
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caudal neuropore closes what day
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26
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