Central Nervous System ( Finals ) Flashcards
gives rise to neurons, glial cells (astrocytes and oligodendrocytes), and ependymal cells
Neuroepithelium
cells have processes which contact the inner and outer surfaces of the neural tube; they undergo mitotic division
Neuroepithelial
loses contact with surfaces of the neural tube and migrate toward the center of the neural tubewall
Neuroblasts and glioblasts
are derived from mesoderm associated with invading blood vessels
Microglial
Accumulated neuroblasts and glioblasts form what layer?, a zone of high cell density in the wall of the nerual tube
mantle layer
that remain lining the neural cavity are designated as what cells?
ependymal cells
that remain lining the neural cavity are designated ependymal cells; they form what kind of layer?
ependymal layer
Surrounding the mantle layer, a cell- sparse zone where axons of neurons and some glial cells are present is designated the?
marginal layer
The mantle layer becomes what matter?
gray matter
The mantle layer becomes gray matter and the marginal layer becomes what matter of the CNS?
white matter
The lateral wall of the neural tube is divided into?
two regions (plates)
A bilateral indentation evident in the neural cavity called?
sulcus limitans
A bilateral indentation evident in the neural cavity (the sulcus limitans) serves as a landmark to divide each lateral wall into an?
alar plate (dorsal) and a basal plate (ventral)
Midline regions dorsal and ventral to the neural cavity constitute, respectively, what plates?
roof plate and the floor plate
This plate contains efferent neurons that send axons into the PNS
basal plate
This plate contains neurons that receive input from the PNS.
alar plate
Generally, neurons are incapable of ?, so all neurons must be formed during nervous system development
cell division
Generally, neurons are incapable of cell division, so all neurons must be formed during nervous system development. However, in hippocampus and olfactory bulb, what persist and can give rise to a small number of new neurons postnatally.
some stem cells or neuroblasts
is generally long and often encased in a myelin sheath formed by glial cells.
axon
Unstained myelin has what color?
white color
This matter refers to CNS regions that have a high density of myelinated axons
White matter
This matter has sparse myelinated axons and generally a high density of neuron cell bodies
Gray matter
removing excess material to achieve a desired effect
Sculpting
To ensure that all targets get sufficient innervation, what development produces an excessive number of neurons along with a profuse, random growth of neuronal processes?
initial neural development
What will degenerate and disappear if they fail to contact an appropriate target due to insufficient neurotrophic molecules?
Neuron
What molecules are released by target cells to nurture neurons?
Neurotrophic molecules
Initially, individual neurons innervate an excessive number of muscle fibers and individual muscle fibers are innervated by a number motor neurons
Neuromuscular Innervation
What neurons will innervate only,about 10% of their initial muscle fibers and individual muscle fibers will retain only a single neuromuscular synapse
motor neurons
What released more neurotransmitter per terminal branch
survivors (winners)
In human prefrontal cortex, synaptic density peaks during what year of age (80K/neuron)?
first year
In the human prefrontal cortex, synaptic density peaks during the first year of life at approximately 80,000 synapses per neuron. What stage of life has half that synaptic density?
Adult
cranial end of the neural tube forms how many vesicles?
three vesicles
cranial end of the neural tube forms three vesicles
(enlargements) that further divide into how many primary divisions of the brain?
five primary divisions
Caudal to the brain the neural tube develops into?
spinal cord
What flexure occurs at the level of the midbrain
midbrain flexure
What flexure appears at the junction between the brain and
spinal cord (it persists slightly in domestic animals)?
cervical flexure
What flexure is concave dorsally (the other flexures are concave ventrally)?
pontine flexure
What becomes central canal lined by ependymal cells
neural cavity
growth of alar and basal plates, but not roof and floor plates, results in symmetrical right and left halves separated by what fissure or septum?
ventral median fissure and a dorsal median fissure (or septum)
the mantle layer develops into what matter?
gray matter
the marginal layer becomes what matter?
white matter
alar plates move laterally and the cavity of the neural tube expands dorsally forming a?
fourth ventricle
the roof of the fourth ventricle (roof plate) is stretched and reduced to a layer of ependymal cells covered by?
pia mater
the roof of the fourth ventricle (roof plate) is stretched and reduced to a layer of ependymal cells covered by pia mater and what develops bilaterally in the roof of the ventricle and secretes cerebrospinal fluid
choroid plexus
What plate is positioned medial to the alar plate alar plate and ventral to the fourth ventricle;
basal plate
white and gray matter becomes what? In fourth ventricle?
intermixed
Adult cerebellum features surface gray matter, called?
cerebellar cortex
Adult cerebellum features surface gray matter, called cerebellar cortex, and three pair of ? located deep within the cerebellar white matter
cerebellar nuclei
What are the first evidence of cerebellar development; the lips are expansions of the alar plate into the roof plate
bilateral rhombic lips
rhombic lips merge medially, forming a?
midline isthmus
deep cells migrate (pass the superficial cells) toward the cerebellar surface and becomes what cell of the cerebellar cortex?
Purkinje cells
neurons of the superficial layer migrate deeply and becomes?
cerebellar nuclei
neuroblasts located laterally in the rhombic lip migrate along the outer surface of the cerebellum, forming an?
external germinal layer
populations past one another allows connections to be established between neurons of the respective populations
Migration of neuron
Neurons that fail to connect are destined to?
degenerate
the neural cavity of the midbrain becomes?
mesencephalic aqueduct
alar plates of midbrain form two pairs of dorsal bulges which become?
rostral and caudal colliculi
the basal plate of midbrain gives rise to what Cranial Nerves which innervate muscles that move the eyes?
oculomotor (III) and trochlear (IV) nerves
midbrain is the rostral extent of what plate?
basal plate
What is the part of brain that are derived entirely from alar plate
Forebrain
the neural cavity expands dorsoventrally and becomes the narrow?
third ventricle
- What is stretched? and 2. what develop bilaterally in the roof of the third ventricle and secrete cerebrospinal fluid
- roof plate
- choroid plexuses
the floor of the third ventricle gives rise to the?
neurohypophysis
the mantle layer of the diencephalon gives rise to?
thalamus and hypothalamus
What nerve develops from an outgrowth of the wall of the diencephalon?
optic nerve
bilateral hollow outgrowths become?
right and left cerebral hemispheres
bilateral hollow outgrowths become right and left cerebral hemispheres; the cavity of each outgrowth forms what ventricle that communicates with the third ventricle via an interventricular foramen?
lateral ventricle
at the midline, the rostral end of the telencephalon forms the? of the third ventricle
rostral wall
the mantle layer surrounding the lateral ventricle in each hemisphere gives rise to?
basal nuclei and cerebral cortex
cellular migrations that form cerebral cortex: from the mantle layer, cells migrate radially to the surface of the ?, guided by glial cells that extend from the ventricular surface to the outer surface of the cerebral wall
cerebral hemisphere
What wave (which becomes the deepest layer of cortex) migrates to the surface of the cortex?
first wave
What wave (which forms the next deepest layer of cortex) migrates to the cortical surface, passing through first wave neurons which are displaced to a deeper position?
second wave
are established within the cerebral cortex as waves of newly arriving neurons migrate through populations of neurons that arrived earlier
Cell connections
