Development of the CNS Flashcards
When does neurulation begin
Week 4
Where does the neural tube initially come from
5th somite
When does the cranial neuropore close
25 days
When does the caudal neuropore close
27 days
Where does the spinal cord develop
caudal to 4th pair of somites
What happens to the wall of the neural tube
Lateral walls thicken, reducing the size of the neural canal until only a central canal exists.
What is the neural tube composed of
pseudostratified, columnar epithelium
What are the three layers of the neural tube
ventricular zone
intermediate zone
marginal zone
What cells are in the neuroepithelial zone
neuroepithelial cells closes to lumen, divide and migrate
What cells are in the intermediate zone
cells differentiate into neurons/glia
What cells are in the marginal zone
decreased cell bodies, contains axon that will be myelinated
What happens if there is a failure of site 1 closure
spina bifida cystica
what happens if site 2 doesn’t close
meroencephaly (anencephaly)
What happens is sites 1, 2, and 4 don’t close
cranioachischisis
How is site five closed
secondary neurulation
What causes SB occulta
unfused neural arch
What happens in SB with meningocele
meninges extrude
What happens with SB w/meningomyelocele
meninges and neural tissue extends
What happens with SB w/myeloschesis
open neural tissue
Where do glioblasts form from
differentiate from neuroepithelial cells
What do glioblasts become
astrocytes and oligodendrocytes
What do glial cells turn into
ependymal cells
what are microglia cells derived from
mesenchyme
What controls proliferation and patterning of neuroepithelial cells
SHH
What do cells in the alar plates form
dorsal gray columns, make kafferent nuclei and form dorsal gray horns
What do cell bodies in the basal plates form
ventral and lateral gray columns
What type of nuclei are formed in basal plates
efferent nuclei, make ventral gray and lateral gray horns
What is the ventral median septum
As basal plates enlarge, form a bulge ventrally on each side
What is the ventral median fissure
deep longitudinal groove formed on teh ventral surface of the ventral median septum
What functions do the basal columns have
motor functions
