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73 Cards in this Set

  • Front
  • Back
the zygotic ends at week __ with the formation of the ___
week 2; embryonic disc
the embryonic stage ends at __ wks with the formation of the ___
week 8; neural tube
the majority of myelination occurs prenatally/postnatally?
postnatally
the majority of neurons are formed prenatally/postnatally?
prenatally
5 stages of neural development?
1. neurulation
2. proliferation
3. migration
4. differentiation
5. synaptogenesis / targetting
neurulation occurs prenatally/postnatally?
totally prenatally
the PNS is derived mainly from ___
neural crest cells
2 parts of the blastocyst and what they form
1.trophectoderm - the placenta
2.inner cell mass - everything else, including the embryo proper
2 parts of the embryonic disc and what they form
1.epiblast - forms the embryo proper
2.hypoblast - forms part of the yolk sac
describe the process of gastrulation.
3rd week
in the embryonic disc, epiblast cells migrate medially and dive down into the center of the embryonic disc, creating the primitive groove. the first epiblast cells that dive in become the endoderm. the next epiblast cells that dive in become the mesoderm. the epiblast cells that dont dive in become the ectoderm
what germ layer forms the excretory system and gonads?
mesoderm
what germ layer forms the glands, including the pancreas and liver?
endoderm
the notocord is formed from ___
midline axial mesoderm
the ___ induces ectoderm to become neural tissue
notocord
what is the neural plate?
prior to neurulation, the notocord induces the overlying ectoderm to thicken and differentiate into neurectoderm, which makes up the neural plate.
the part of the neural plate that is midline and directly over the notocord
floor plate
the part of the neural plate found at its lateral margins
neural crest
what is primary neurulation
when the sides of the neural plate fold up to form the neural tube
what is the neural groove?
the midline fold of the neural plate as the neural folds rise up to become the sides of the neural tube
what causes closure of the neural tube? what time does this occur?
4th week

the neural folds are brought close together and form cell-cell junctions at the dorsal midline.
what is wedging?
the change in cell shape in parts of the neural tube where the basal domain becomes much larger than the apical domain resulting in a hinge point.
where does neural groove begin to fuse?
the 4th somite. extends rostrally and caudally. rostral neuropores fuse first
how does segmentation of the rostral neural tube occur?
there are constrictions dividing the rostral neural tube into 3 vesicles: the prosencephalon, mesencephalon, and rhombencephalon. some sections have weaker cell-cell interactions and are more easily expanded by fluid pressure (blown up like a balloon?)
what is flexure of the neural tube?
the cephalic flexure occurs at the mesencephalon allowing the forebrain to tuck under the hindbrain. the cervical flexure occurs b/t the hindbrain and spinal cord and allows for bulging and segmentation.
where and why is there a transient blockage in the neural vesicles?
between the hindbrain and spinal cord during the bulging of segmentation.
what parts of the ventricular system do the vesicle cavities form?
prosencephalon - 1,2,3 ventricles
mesencephalon - cerebral aqueduct
rhombencephalon - 4th ventricle
the apical pole cells of the spinal cord face ___
the central canal
basal and apical pole cells are linked by _____
junctional complexes
the furrow between the alar and basal plates?
sulcus limitans
which neurons of the PNS do not arise from the neural crest cells?
1. motor neurons - their cell bodies lie in the ventral horn and their axons grow into the somites
2. preganglionic autonomic neurons - their cell bodies lie in the lateral horn (symp) or in the brain? (para)
3. placodal ectoderm gives rise to certain cranial nerve sensory neurons.
ex. sensory epithelia of the nose, inner ear, lens, some neurons of the sensory ganglia
what is the placodal ectoderm?
the area just outside the neural crest. not neurectoderm. gives rise to sensory epithelia of the nose, inner ear, lens, ant. pituitary, and some neurons of sensory ganglia of cranial nerves
origin of the sensory epithelia of the nose and inner ear?
placodal ectoderm
give rise to the branchial arches and periocular tissues
cranial neural crest cells
give rise to melanocytes, schwann cells, chromaffin cells, and others
trunkal neural crest cells
malignant melanoma is a tumor associated w/ __
NCC's (melanocyte)
neurofibromatosis is a tumor associated w/ __
NCC's
caused by inappropriate closing of the posterior neural tube during the first month of pregnancy (wk 4?)
spina bifida
caused by failure of the anterior neural pore to fuse
anencephaly
a herniation of brain tissue through a hole in the skull
encephalocoele
failure of the lobes of the brain to separate
holoprosencephaly
condition in which the cerebellar tonsils slip into the foramen magnum
Arnold Chiari formation
what is the placodal ectoderm?
the area just outside the neural crest. not neurectoderm. gives rise to sensory epithelia of the nose, inner ear, lens, ant. pituitary, and some neurons of sensory ganglia of cranial nerves
origin of the sensory epithelia of the nose and inner ear?
placodal ectoderm
give rise to the branchial arches and periocular tissues
cranial neural crest cells
give rise to melanocytes, schwann cells, chromaffin cells, and others
trunkal neural crest cells
malignant melanoma is a tumor associated w/ __
NCC's (melanocyte)
neurofibromatosis is a tumor associated w/ __
NCC's
caused by inappropriate closing of the posterior neural tube during the first month of pregnancy (wk 4?)
spina bifida
caused by failure of the anterior neural pore to fuse
anencephaly
a herniation of brain tissue through a hole in the skull
encephalocoele
failure of the lobes of the brain to separate
holoprosencephaly
condition in which the cerebellar tonsils slip into the foramen magnum
Arnold Chiari formation
in humans, the ___ induces the ectoderm to become the nervous system by blocking ___
notocord; BMP
noggin, chordin, and follistatin block the ____ signalling pathway
BMP
___ acts on the ectoderm to cause formation of epidermis
BMP
the default pathway of the ectoderm is development into ___
neural tissue
fusion of the neural folds require the cell adhesion molecules ___ and ____
N-cadherin and N-Cam
gradients of molecules establish dorsal-ventral patterning of the neural tube. the dorsal epidermis establishes a gradient of __ and the notocord establishes a gradient of ___
dorsal epidermis - BMP (BMP 4,7,and dorsalin)

notocord - Sonic hedge hog (Shh)
what establishes the alar and basilar plates of the spinal cord
a dorsal gradient of BMP established by the dorsal epidermis

a ventral gradient of Sonic hedge hog established by the notocord
holoprosencephaly results from a mutation of ____
Shh (sonic is such a bastard!)
Wnt, BMP, retinoic acid, and FGF are examples of ____
anteriorizing and posteriorizing factors
transcription factors differentially expressed along the anterior-posterior axis that regulate other transcription factors involved in development
hox (homeobox domain) genes
describe the process of corticogenesis
the whole brain develops from a single layer of neuroepithelium
"progenitor cells" capable of becoming cortical neurons or glia proliferate in the ventral epithelium. they then migrate to the intermediate zone and then along radial glia to the cortical plate. layer VI (the innermost layer) forms first. Layer I forms last. the cortex forms from the inside outwards. the cells destined to become glia keep dividing once they reach the cortical plate
why does the ventricular epithelium appear pseudostratified?
it is the proliferative zone, and the cells are at different stages of proliferation. the nucleus changes relative position as the cells prepare to divide and divide.
ApoER2 and VLDLR are two signalling receptors involved in ____
neuronal migration (to the cortex)
___ span the length of the cortex and allow for a high degree of correspondence b/t where neurons are produced and where they migrate to in the cortex
radial glia cells
where does neurogenesis occur postnatally?
hippocampus
subventricular region of the cortex
Reelin is an extracellular matrix molecule involved in ____
migration
cell adhesion molecules like N-Cam and N-cadherin, along with neurotrophic factors like BDNF are important in which stage of nervous system development?
synaptogenesis /targetting
which stage of nervous system development does not end until six months postnatally
differentiation
proneural genes and gliogenic genes
genes whose expression determine whether a progenitor cell will develop into neuron or glia
when neurons lose in the competition for neurotrophic factors, what happens?
they undergo synaptic elimination or apoptosis
which cells in the brain are not derived from neurectoderm?
microglia