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29 Cards in this Set
- Front
- Back
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What is Dorsal Induction? At what stage of gestation does it take place?
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Primary neurulation and caudal neural tube formation aka secondary neurulation. Peak time of occurrence is 3-4 weeks of gestation.
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What days does the closures occur? (4)
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1. 22 days - fusion begins in the lower medulla
2. 24 days - anterior end closes 3. 26 days - posterior end closes 4. 28-32 days - caudal area forms via canalization. Peak time is 4-7 weeks gestation. Filum terminale and cauda equina form. |
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Name 5 disorders of dorsal induction/neural tube defects?
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1. Anencephaly
2. Encephalocele 3. Myelomeningocele 4. Occult states 5. Tethered Filum |
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What time period would dorsal induction defects occur?
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Within the first 4 weeks of gestation.
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What is Anencephaly?
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Absence of the brain
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What is encephalocele?
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Opening in the back of the skull
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What is myelomeningocele?
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Spina Bifida
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What is Occult States?
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States of spina bifida that you cannot see because they are covered by the skin.
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What is tethered filum?
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Filum terminale gets stuck to the end of the spinal canal.
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What is Ventral induction? And when does it occur?
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aka prosencephalic development. Development of the face, forebrain, corpus callosum, septum, optic nerve, chiasm, hypothalamic structures. Occurs at 2-3 months gestation, 5-6 weeks.
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What types of defects could occur during ventral induction?
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Cleft lip/palate, forebrain and midbrain deformities.
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What is:
1. Aprosencephaly? 2. Holoprosencephaly? 3. Atelencephaly? |
1. Failure of teh telencephalon (forebrain) and the diencephalon (midbrain) to form.
2. Marked deformation of the telen and dien. 3. Failure of the telencephalon to form. |
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When could ventral induction disorders occur?
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5/6th week, 2-3 months of gestation.
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Other disorders of Ventral Induction other than face and fore/mid brain.
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-Agenesis of corpus callosum
-Agenesis of septum pellucidum -Septo-optic dysplsia -Congenital Hydrocephalus |
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Where does Neuronal Proliferation occur and when does it occur?
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Occurs at the ventricular and sub-ventricular zones where all the neurons originate from. Occures at 2-4 months gestation with peak time at the 3 or 4th month.
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What are two common disorders with neural proliferation disorders?
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Microcephaly - too few neurons.
Macrocephaly - large brain, too many neurons. No deformities as the brain is usually well formed. May be seen in achondroplasia, neurofibromatosis, Sturge-Weber syndrome, sclerosis and Fragile X syndrome. |
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What is Neural Migration?
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When millions of nerve cells move from the ventricular/subo-ventricular zones to the CNS location where they will ultimately reside.
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During what stage of gestation does neural migration occur?
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3-5 months.
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Disorders of neuronal migration are characterized by...
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Disturbances in neural function, seizures, aberration of gyri development.
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Name four disorders of neuronal migration.
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1. Schizencephaly
2. Lissencephaly 3. Pachygyria 4. Polymicrogyria |
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What is Schizencephaly?
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complete agenesis of portions of the cerebral wall leaving seams or clefts. Parts of the brain that didn't form
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What is Lissencephaly?
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Smooth brain with very few or no gyri
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What is Pachygyria?
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few gyri with a broad thick cortical plate.
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What is Polymicrogyria?
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A great number of very small plications in the cortex. Brain looks prune-like, wrinkled instead of clear cut gyri and sulci.
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What is neuronal organization and when does it occur?
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It is the establishment and differentiation of subplate neurons. The attainment of proper alignment, orientation and layering of cortical neurons. ESTABLISHES SYNAPSES.
Occurs in the 5th month of gestation to several years after birth. Helps children learn, neural plasticity |
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What is pruning?
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Natural cell death via selective elimination of neuronal processess/synapses. Approx. 50% of cells die before final maturation via genetically coded. Failure of cell death may have major implications. Theory of autism, don't go through pruning so there are too many connections, hypersensitive.
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What are some disorders of neuronal organization?
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1. Mental retardation w/ or w/o seizures.
2. Fragile X syndrome 3. Down Syndrome, fewer synaptic connections 4. Perinatal insults before baby was born 5. Autism 6. Duchenne Muscular Dystrophy |
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What is myelination and when does it occur?
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Acquisition of myelin membrane around axons. Most rapid after birth, so it is important to keep measuring babies head. Occurs from the 2nd trimester (6 months gestation) through adulthood.
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Disorders of myelination include (3) which result in (2).
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1. Perinatal insults
2. Metabolism 3. Malnutrition 1. Decreased postnatal head growth. 2. Cerebral white matter disturbance, where myelin is being laid down. |
