embryo II Flashcards
How does the neural tube form
begins with formation of neural plate, lateral edges elevate and make neural groove
the neural groove then fuses
when do the cranial and caudal neuropores of the nueral tube close
cranial closes day 25
caudal closes day 27
what does the neural tube become
brain and spinal cord
Where do neural crest cells come from
neuroectoderm as the neural tube is closing
what do cranial neural crest cells become
bones, cartilag, fascia, ligaments and tendons of face and neck
sensory ganglia, autonomic ganglia
what do the spinal neural crest cells become
DRG, autonomic ganglia and the fibrous skeleteon of heart
what do both the spinal and cranial neural crest cells become
meninges schwann cells and melanocytes
which part of neural tube becomes spinal cord
caudal to 4th pair of somites
what are the 3 different regions that form in the nueral tube because of migration
ventricular, mantle and marginal zones
In the embryo what is the ventricular zone in neural tube
neuroepithelium-pseudostratified
gives rise to neurons and glia
In the adult what is the vetnricular zone from neural tube
simple layer ependymal cells
What is the mantle zone of spinal cord in development
superficial to neuroepithelium
neuronal cell bodies
have alar and basal plates that are separated by sulcus limitans
what do the alar and basal plates become in development of spinal cord
alar forms sensory dorsal horn
basal forms motor ventral horn
describe marginal zone of spinal cord developmentally
outermost layer, have nerve processes like axons and dendrites
What type of cells come from neuroepithelium
neuroblasts and gliablasts
what do the neuroblasts become
ventral motor horn neurons and dorsal sensory horn neurons
what do the gliablasts become
astrocytes and oligodendrocytes
What make up a spinal n
ventral nerve root + dorsal nerve root
dorsal spinal nn inn what areas
muscles skin joints of back
ventral rami from spinal nn inn what areas
limbs, ventral body wall
What are the vesicles in the cranial part of neural tube
prosenecephalon (forebrain)
mesencephalon (midbrain)
rhombencephalon (hindbrain)
what are the portions of the prosencehalon
telencephalon and diencephalon
what are the portions of the rhombencephalon
metencephalon
myelencephalon
what are the flexures of the cranial portion neural tube
cervical, cephalic and pontine
what are the ventricles of the brain derived from
4th- lumen rhombencephalon
cerebral aquaduct- lumen mesencephalon
3rd- lumen of diencephalon
lateral- lumen of telencephalon
what develops to become choroid plexus
tela choroidea which is pia mater and ependymal cells
what areas of the brain make up the brainstem
mesencephalon and rhombencephalon
how does gray matter differ as the alar and basal plates ascend into brainstem
discrete nuclei instead of columns, sensory nuclei are displaced laterally b/c of pontine flexure
what is the myelencephalon
medulla
what CN is the myelencephalon associ with
VIII IX X XII
what layer of nueral tube forms most of pons
marginal layer
what CN are assoc with the metencephalon
V VI VII VIII
what is the metencephalon
pons
what forms the cerebellum
alar plates of metencephalon (rhombic lips)
fuse and form cerebellar plate
how come gray matter is external and white matter internal
waves of neuroblasts migrate from alar plate through marginal layer to form outer cerebellar cortex
What forms midbrain
mesencephalon
what CN are assoc with mesencephalon
III IV
What structures arise from diencephalon
optic vessels(CN II), pineal gland, thalamus, hypothalamus, pituitary gland
what is in the epithalamus
choroid plexus and pineal gland
what do the alar plates become in diencephalon
2 swellings separated by hypothalamic sulcus
superior-thalamus
inferior-hypothalamus
describe where neurohypophysis and adenohyphysis come from
neurohypophysis from downgrowth of diencephalon neuroectoderm
adenohypophysis from upgrowth of oral ectoderm
What does the telencephalon become
cerebral hemispheres and corpus striatum
describe how in cerebral Cx gray matter is superficial
waves of neuroblasts migrating through radial glial cells in marginal zone, youngest cells form most external layer
what is the corpus striatum
swelling in floor of cerebral hemispheres
what CN is assoc with telencephlaon
olfactory tract and bulb
What are the main spinal neural tube defects
spina bifida occulta
spina bifida cystic
What is meroencephaly or anencephaly
failure of brain to form
what is craniorachischisis
closure defect of cranial end neural tube extends into spinal cord
what is microcephalys
small cranium from brain undervelopment
What causes an encephalocele
defect in skull (usually occipital) allowing portions of CNS to protrude in cyst like way from skull
what is a meningocele
only meninges bulge through defect in skull
what is a meningoencephalocele
meninges and part of brain bulge into defect of skull
what is an meningohydroencephalocele
meninges, brain, and part of ventricular system bulge thorugh skull
what is congenital hyrocephalus
increased CSF within ventricles, imbalance of production and absorption CSF
results in dilation of ventricles and skull expands
causes thinning of bones of calvaria
What is Arnold chiari syndrome
herniations of cerebellar hemispheres through foramen magnum; underdevelopment of posteiror cranial fossa
often assoc with spina bifida cystica
what is holoprosencephaly
failure of forebrain neural tube to form cerebral hemispheres.
fore brain is underdeveloped and the lateral ventricles are fused
what is the only endocrine gland to come from neural tube
pineal gland
what is the cranial-most portion of neural tube
diencephalon, because lamina terminals closes there
root cause of spina bifida
neural tube does not fuse, so then vertebral arch does not fuse (posteriorly)
what are the 2 most common sites of ventricular blockage
interventricular foramina
cerebral aquaduct
