Nervous System Dev. Flashcards
What structures develop from the telencephalon?
Telencephalon- which develops into paleocortex, corpus striatum, neocortex
Describe stages of neural tube wall from simple cuboidal to stratified.
Early Neural: simple cuboidal
Neural plate: simple columnar
Early neural tube wall: psuedostratified epi
Late neural tube: stratified epi
What is the importance of the orientation of metaphase plate during proliferation of cells within the neural tube.
If the plate is perpendicular to inner margin the daughter cells will stay proliferative
If it is parallel the daughter cells closest to the lumen will be proliferative
Describe the heirarchy of basic cell lineages in development of nervous system, Also when mitosis cease in lineage and differentiation begins
Glial lineage progenitor cell and Neuronal lineage progenitor cell. Neuronal lineage mitosis stops.
Glial lineage goes into radial progenitor and 0-2a progeintor cells with mitosis
What is the effect of the graft secondary notochord near neural tube?
Induces a secondary floor plate
What is the effect of removing the notochord?
The spinal cord is disorganized and has multiple exit sites of nerves
What is the effect of slitting neural plate on one side of the floor plate?
Slitting neural plate on one side of floor plate removes the wall of neural tube from influence of notochord allowing disorganized exit of nerve fibers
What is the signaling pathway and factors that establish the dorsal ventral axis of developing neural tube
Ventral signaling: formation of floor plate of neural tube via Shh and Shh from floor plate induces formation of motor neurons
Dorsal: ectoderm flanking neural plate uses BMP’s to induce Snail-2 in future neural crest to maintain Pax3 and 7 to create dorsalizing effect.
(Pax-3 and 7 is suppressed by Shh from floor to suppress dorsalizing effect in basal plate)
What roles do the notochord and non nervous ectoderm play?
d
Cranial nerve 5 relationship to rhombomeres and pharyngeal arches?
CN V is equivalent to rhombomere 2 in birds and innervates structures derived from first pharyngeal arch
Cranial nerve VII relationship to rhombomeres and pharyngeal arches?
equivalent to rhombomere 4 in birds innervates structures derived from second pharyngeal arch
CN IX relationship to rhombomeres and pharyngeal arches?
Equivalent to rhombomere 6 in birds innervates structures from third pharyngeal arch
How is the segmented nature of spinal nerves related to somitic mesoderm pattern?
The segmented nature is due to the pattern of somitic mesoderm along the neural tube. Motor neurons can penetrate anterior mesoderm of somites but not posterior.
what is the role of isthmic organizer and what signaling TF are involved?
Located between the mesencehpaon and metencephalon its organizes and polarizes the dorsal midbrain and cerebellum. Principal signaling molecule is FGF-8 posteriorly also expresses Wnt-1 anteriorly.
FGF-8/Wnt1 induces expression of En-1, En-2 Pax-5 and 2.
How does shh determine midbrain dorsoventral axis?
Shh restricts expression of Pax-7 which is related to formation of alar plate. Pax-6 is expressed in alar plate of diencehpaon and is master gene of eye. Pax-6 inhibits En-1 and vice versa.
What role do prosomeres P1-P3 play in forebrain patterning?
Forebrain segmentation is represented by it. P1-P3 defines diencephalon and P2-P3 defines dorsal and ventral thalamus
Refer to text for relation between Shh and holoprosencephaly?
Shh induces the ventral forebrain to form and be organized. In the absence of Shh tissues of forebrain are reduced leading to fusion called holoprosencephaly.
Describe steps in outgrowth of motor neuron?
Axons grow from motor neuroblasts in the basal plate of spinal cord, boundary caps created by neural crest cells maintain separation between CNS and PNS.
Sensory neurons come from neural crest and cell bodies form sensory spinal ganglia Axons grow to and aaway from spinal cord. and boundary caps maintain separation
List cues involved in axon guidance.
Caudal half of somite, Fibronectin and laminin, integrins and cadherins
What are pioneering axons?
In periphreal nerves one pioneering axons is the axon that precedes the others in growth towards the target
Describe steps in formation of synaptic junction.
- Halting of axonal extension
- Induction of synaptic vesicles releases sites
- Synaptic release of ACh
- Accumulation of Acetylcholinesterase
- cluster of Ach receptors
- elimination of nonjunctional ACh receptros
- Formation of postynaptic folds
What role does apoptosis play in establishment of neurite and end organ connections?
When axons fail to reach their targets death eliminates them. Cell death reduces the size of the neuronal pool needed for the size of the target. Cell death compensates for presynaptic input that’s too small to accomodate life. Neuronal cell death also eliminates connection errors between neurons and specific organs.
Describe steps in origin of sympathetic preganglionic neurons compare with parasympathetic preganglionic neurons.
Sympathetic preg. motor neurons come from lateral horns of grey mater.
Parasympathetic preg. come from midbrain, hindbrain, and S2-S4
What factors determine whether migrating neural crest cells differentiate into autonomic neurons or other neural crest derivatives?
BMP’s determine this
Cholinergic differentiation factor.
Natural transition of neurotransmitter from noradrenergic to cholinergic in the symp innervation of sweat glands depends on cholinergic differentiation factor a glycosylated 45-kD protein.
Hirschsprung’s disease?
Newborn with complete constipation w/o physical obstruction it is usually absence of parasympathetic ganglia from sigmoid colon and rectum
What structure develops from the diencephaon?
Epithalamus
Thalamus
Hypothalamus
Infundibulum
What structure develops from the mesencehpaon?
tectum, tegmentum, cerebral peduncles
What develops from the metecephalon?
cerebellum and pons
What develops from the myelencephaon?
Medulla
What develops from the prosencephalon?
telencephalon and diencephalon
What develops from the mesencephaon?
Mesencephalon
What develops from the rhombencephalon?
Metencephalon and myelencephalon
What role do netrins and semaphorins play?
Netrins are attractant and semaphorins are repulsive
What are boundary caps and what role do they play in axon growth?
Boundary caps are created by neural crest cells to maintain separation between CNS and PNS
What are growth cones??
expanded region of cytoplasm with filopodia they advance through extension/resporption cycles involving actin microfilaments
