Neuro 2 Flashcards
wall of neural tube is composed of neuroepithelial cells that continue to divide giving rise to
neuronal, ependymal, and glial progenitor cells
what are the 3 layers of embryonic neural tube
ventricular zone (germinal layer)
mantle layer
marginal layer
germinal layer composed of
activating, dividing cells; various cells born that migrate away
what zone is closest to the neural canal
ventricular zone
ependymal cells form what
a simple cuboidal epithelium lining that remains attached to the internal limiting membrane of the cavities of the CNS
ependymal cells persist in adult to line
ventricles and central canal of spinal cord; form choroid plexus
germinal layer active cell division; dividing cells move to
mantle layer
what is the intermediate zone
the mantle layer
what is the mantle body composed of cell bodies of
proliferating neuroepithelial cells (immature neurons and glial cells)
mantle layer ultimately becomes
gray matter of CNS
What is the outer zone
marginal layer
what is the marginal layer composed of
axon processes of developing neurons (primary component myelinated axons)
marginal layer becomes
white matter of CNS
Neural crest cells become
GSA neurons postganglionic GVE neurons (symp and parasymp) PNS glial cells melanocytes adrenal chromaffin cells (epinephrine) arachnoid and pia mater various other non-neuronal cells
left and right dorsal thickenings of mantle layer become
alar plate
alar plate becomes
interneurons,sensory relay neurons
left and right ventral thickenings of mantle layer become
basal plate
basal plate becomes
motor neurons
left and right longitudinal grooves form on inner wall of neural canal and become
sulcus limitans
sulcus limitans is the boundary between
dorsal sensory alar plate and ventral motor plate
alar and basal plates do what
expand and fuse forming characteristic butterfly-shaped gray matter of spinal cord
alar plate becomes ______ horns
dorsal horns
basal plate becomes ______ horns
ventral and intermediate horns
sulci of neural canal eventually disappear and canal
reduces in diameter to become central canal
right and left sides remain ___ on the surface
demarcated
dorsal median groove
shallow depression
ventral fissure
deep groove
motor neuron axons will emerge ____
ventral roots
GVE migrate to
junction of alar and basal plates (intermediolateral gray horn) and move to target
what is the target at this time
somites!
fusing and reshaping of somites creates
limbs
gsa neuron processes are ___ derived
neural crest derived
gsa neuron processes grow into
dorsal roots and out spinal nerve
cell bodies of gsa
dorsal root ganglion
dendrites to receptor become
spinal nerve
axons become
dorsal root
early brain development require
closure of rostral neuropore to be normal
3 dilations form at ____ end of neural tube
rostral end
the rostral end of neural tube is
primary vesicles (follows closure of neural tube
what are the 3 dilations
proencephalon
mesencephalon
rhombencephalon
2 bends or flexures develop
cervical flexure and cephalic flexure
cervical flexure between
rhombencephalon and developing spinal cord
cephalic flexure occurs in
mesenchephalon
cervical flexure persists in what species
in all species as accomodation of head and neck
cephalic flexure temporary in
quadrapeds
cephalic flexure persists in
bipeds (primates)
prosencephalon and rhombfencephalon subdivide forming
a total of 5 secondary vesciles
prosencephalon divides into
telencephalon and diencephalon
telencephalon becomes
cerebral cortex and basal ganglia and hippocampus
diencephalon becomes
thalamus, hypothalamus, retina
rhombencephalon divides into
metencephalon and mylencephalon
metencephalon becomes
pons and cerebellum
mylencephalon
medulla oblongata
pontine flexure forms and begins separation of
metencephalon into pons and cerebellum
neural canal expands and persists as _____
ventricular system within each secondary vesicle
neural canal lined by
ependymal cells
telencephalon contains
lateral ventricles
diencephalon contains
3rd ventricle
mesencephalon becomes
mesencephalic aqueduct
metencephalon contains
4th ventricle
myelencephalon contains
4th ventricle
csf is produced by
choroid plexus (ependymal cell origin)
csf production is _____ independent
pressure
csf produced by
lateral, 3rd, 4th ventricles
organization of brain development
initial pattern similar to spinal cord with alar and basal plates (alar sensory, basal motor)
in brainstem, as progress dorsal aspect thins,
alar plate moves laterally pushing basal plate medially
more _____ parts lose this organization
rostral
neural tube fails to develop normally along some part of its
length
structure ____ to neurotube rquire neurotube to develop normally
dorsal
spina bifida
failure to close caudal end of neural tube in what will beocme spinal cord or rupture of caudal neuropore (defect in primary neurulation)
failure to close cranial neural tube affects
the brain and head
failure to close entire neural tube is a lethal condition called
cranioarchischisis
spina bifida occulta is a defect in
vertebral arch in which no material extends out of vertebral canal; skin covers defect;
what neurological symptoms do you see with spina bifida occulta
minimal to none
spina bfida + meningocoele
defect in vertebral arch; CSF fill sac of meninges protrude, no spinal cord tissues protrude; most covered by skin
what neurological signs do you see with spina bifida +meningocoele
minimal
muscle mass in spina bifida + meningocoele
no muscle mass where defect is
spina bifida + meningomyelocoele
defect in vertebral arch, meninges & spinal cord bulge out of vertebral canal; CSF filled sac of meninges with disorganized spinal cord tissue protrude; most NOT covered by skin;
spina bifida + meningomyelocoele neurological sings
disorganized neural tissue and neurologic damage to nerve roots; moderate to severe neurological symptoms
defect in primary neurulation results in
tail - less; can have urinary and fecal incontinence if sacral cord affected
anencephaly
lethal conditio in which calvarie (bones of skull that surround brain) fails to form around brain;
in ancephaly what happens to the forebrain
fetal forebrain stops developing and remains in contact with amniotic fluid and subsequently degenerates (prosencephalon or forebrain and meninges in region is absent)
exencephaly
defect in skull, brain tissue extends through defect; no skin or meninges cover brain tissue
meningocoele
defect in skull, meninges extend through defect; CSF filled sac of meninges, no brain tissue; may be covered by skin
menigoencephalocoele
defect in skull, meniges and brain tissue extend through defect; brain and CSF filled sac of meninges; may be covered by skin
hydrocephalus
abnormal accumulation of cerebrospinal fluid in cranial cavity within ventricular system and /or subarachnoid space
how does hydrocephalus occur
can be acquired or congenital
what happens in hydrocephalus
disrupt circulation of CSF (obstruction leads to accumulation); elevated CSF pressure compresses neurons (neuron death if pressure not relieved)
if increased pressure occurs prior to closure of sutures
skull expands (domed appearance) on top of head; skull cant dome once sutures fuse
what is the most common obstruction site
mesencephalic aqueduct
cerebellar hypoplasia (atrophy, abiotrophy) is often a rsult of
viral infection during late fetal development at time of rapid cel division (growth)
what viruses can cause this
feline panleukopenia virus (feline distemper)
bovine viral diarrhea virus
1st affects dam, then crosses placenta and invades developing brain of fetus
ddividing cells kille dby
virus (number of cells lost=severity of symptoms)
cerebellar ataxia occurs when
born with too few cells in cerebellum
this causes
disrupt rate, range and force of motion
what sings can you see
over reaching, over-stepping, high stepping; falling
under reahing, short stepping; falling
postures to compensate poor balance and motion control (broad based stance)
