Exam 2 Lecture: Development of the Nervous System Flashcards
What is grey matter made up of?
neuronal cell bodies and glial cells
What is white matter made up of?
myelinated and unmyelinated axons
Why is white matter white?
high lipid concentration of the myelination
Where are tracks of axons located?
in the white matter
What is the ascending track?
a track of axons from the spinal cord to the brain
What is the descending track?
a track of axons from the brain to the spinal cord
What is located in the central canal?
CSF
Dorsal root + ventral root =
spinal nerve
What type of neurons are in the dorsal root?
sensory
What type of neurons are in the ventral root?
motor
True or False: the CNS is the first organ system to initiate differentiation as well as the first to be functional
False, it is only the first to initiate differentiation
When does the formation of the neural tube normally happen?
2-3 days after gastrolation
Of what origin is the neural tube?
the ectoderm
How does the neural fold play a role in the development of the neural tube?
they grow up throughout development, once they contact each other, the neural tube separates from the ectoderm and drifts away from the embryo
Where does the neural tube begin to form at?
the cervical cranial thoracic area
In what direction does the neural tube form?
in a cranial to caudal direction
What are the two communications of the neuropore?
the rostral and the caudal
Where is the neural crest cell located?
on the surface of the ectoderm as the neural folds are trying to make contact
What are the neural crest cell derivatives?
all of the ganglia in the body; sensory ganglia of our cranial nerves, enteric ganglia, dorsal root ganglia, parasympathetic ganglia, synmpathetic ganglia, schwann cells, adrenal medulla
What are the components of the structure of the neural tube?
neural canal, ependymal cells, mantel layer, roof and floor plates
What are the plates of the mantel layer?
basal plate and alar plate
What does the alar plate give rise to?
dorsal horn; sensory predominant structures
What does the basal plate give rise to?
ventral horn; motor structures
What causes the formation of the fissure and sulcus?
created because the roof plate and the floor plate are not doing anything (replicating)
How is the ventral root created?
neurons residing in the ventral horn project their axons out to meet a target
How is the dorsal root created?
neurons residing in the dorsal root ganglia project axons out to the periphery and to the dorsal horn
What causes the cauda equina?
In early development, the sacral nerves join with a muscle on the other side of the vertebra, as the spinal cord begins to see differential growth, the spinal cord moves in a cranial direction thus elongating the root of the nerve to keep the connection with the muscle
What causes spina bifida?
neural tube closing issue
spina bifida occulta
the most mild case of spina bifida, usually only affects 1 vertebra
Myeloschisis
failure of the neural tube to close
Meningiomylocele
meninges prolapses through the area that the vertebral arch should be
What does the brain begin as?
a neural tube with a neural canal inside of it, the body wall in the periphery with a mantel and marginal layer
What is brain development caused by?
dilations (vesicles)
What are the three primary vesicles that brain development begins with?
forebrain, midbrain, hindbrain
What does the forebrain divide into?
2 secondary vesicles (1 and 2)
What does the midbrain divide into?
nothing, remains the midbrain or 3rd vesicle, does not dilate
What does the hindbrain divide into?
2 secondary vesicles (4 and 5)
What does the wall and the cavity of the 1st secondary vesicle become?
wall: central hemispheres
cavity: lateral ventricles
What does the wall and the cavity of the 2nd secondary vesicle become?
wall: thalmus
cavity: third ventricle
What does the wall and the cavity of the 3rd secondary vesicle become?
wall: midbrain
cavity: aqueduct
What does the wall and the cavity of the 4th secondary vesicle become?
wall: pons and cerebellum
cavity: upper part of the fourth ventricle
What does the wall and the cavity of the 5th secondary vesicle become?
wall: medulla
cavity: lower part of the fourth ventricle
What structures are involved in hind brain development?
basal and alar plate(nuclei are derived from this plate)
What structure is vital in forming the cerebellum and pons?
rhombic lip
What are the three layers of the rhombic lip?
external germinal layer, purkinje neurons, cerebellar nuclei
Which layer of the rhombic lip adds to the majority of the bulk of our cerebellum?
the external germ layer
How do the cells of the external germ layer make connections with the purkinje neurons?
they eventually separate from the external germ layer and descent into the cerebellum; this process produces an axon and creates a connection as they pass the purkinje fibers
What does panleukopenia and BVD target?
the external germinal layer
How does the cerebrum layer develop?
cells in the mantel layer begin dividing and get a signal to migrate so they migrate out to the marginal layer. This process of division and migration continues in order to create more and more layers of cells
What is multiple layer migration vital in?
forming the sulcus(depression) and gyrus (elevation)
cerebellar hypoplasia
reduced size of the cerebellum
anencephaly
‘no brain’, rostral neural pore fails to close
lissencephaly
waves of migration did not occur as they should have
cranium bifidum
skull cannot form correctly around the brain
hydrocephalus
increased CSF pressure
Of what is the pituitary gland in origin?
ectodermal
Where does the posterior pituitary develop from?
ectoderm from the forebrain
How is the posterior pituitary connected to the brain?
directly via an axon that is connected to a neuron in the brain
Where does the anterior pituitary develop form?
ectoderm coming from the mouth
How is the anterior pituitary connected to the brain?
the axon connected to the neuron in the brain terminates on the portal vein, then the portal vein connects to the anterior pituitary
