CNS Embryo Flashcards
Brain Development begins when?
3rd week of gestation
What is the first event in brain development
Formation of neural tube and neural crest cells
Brain develops from which of the three germ layers
Ectoderm…brain is just fancy skin
Brain develops into three vesicles at how many weeks gestation
4 (Prosencephalon, Mesencephalon, Rhombencephalon)
Brain develops into 5 vesicles at how many weeks gestation
5
Neural plate formed when
Week 3
Neural Tube formed what week
week 4
Cerebral hemispheres enlarge when
week 8
Neuroblasts form what>
All neurons in the CNS
Neuroblasts differentiate from
Neuroepithelial cells
Glioblasts form what?
Radial glial cells, astrocytes, oligodendrocytes, ependymocytes, tanycyctes, choroid plexus cells
What are radial glial cells
They serve as guide wires for the migration of neurons. Neurons attach to and travel along the radial glial cells to their final destination
What is the sulcus limitans?
Separates the alar plate (Dorsal Sensory neurons) from the basal plate (ventral motor neurons). This remains a useful anatomical marker in the adult brainstem
Neurogenesis in the alar plate forms what
sensory neurons and nuclei of the spinal cord and brain stem
Dorsal root ganglia neurons are derived from which plate?
Alar
Neurogenesis in the basal plate
Motor neurons and nuclei of the spinal cord and brain stem
Which elongates faster, spinal column or spinal cord?
Column….this accounts for the rostral migration of the end of the spinal cord (or the conus medullaris) during fetal development.
Adult spinal cord ends where?
L1-2
3 month fetus= spinal cord ending where?
endo of spinal column
6 mos fetus = spinal cord ending where?
S1
9 mos fetus = conus medullaris where?
L3
Failure of the Anterior Neural pore to close=
Anencephaly and Encephalocele
Failure of the posterior neural pore to close =
Spina Bifida
Meningocele
Myelomeningocele
Neural tube closure defects are closely associated with what
Folic acid deficiency in the mother….
Folic acid supplements takes early in pregnancy, especially during the first few weeks of gestation significantly reduce the incidence of neural tube closure defects
Failure of neural tube closure allows alpha-fetal protein to leak out into the amniotic fluid and into the bloodstream of the mother. Testing for alpha-fetal protein levels in the mother’s blood or via amniocentesis can reveal neural tube defects
ok
SPO
Spina Bifida Occulta…..failure of mesodermal cells to form bony dorsal vertebrae that surrounds the spinal cord…these individuals rarely develop neurological symptoms
SPO clinical symptoms
tuft of hair over the lumbar sacral area
SPA
Spina Bifida Aperta
SPA with Meningocele, the meninges extend into the outpouching
SPA with myelomeningocele, meninges, spinal cord and filum terminale extend into the outpouching
Chiari malformation
displacement of the cerebellar tonsils below the foramen magnum.
Neuroblasts and Glioblasts are generated where
in the ventricular zone
Ventricular zone neuroepithelial cells differentiate into neuroblasts and glioblasts…
Neuroblasts then form all neurons. Glioblasts form glial cells
Microglia arise from …
monocytes in the circulation and invade the CNS during the third week with the formation of cerebral blood vessels.
