Nervous System Dev.

Question 1

What structures develop from the telencephalon?

Answer 1

Telencephalon- which develops into paleocortex, corpus striatum, neocortex

Question 2

Describe stages of neural tube wall from simple cuboidal to stratified.

Answer 2

Early Neural: simple cuboidal
Neural plate: simple columnar
Early neural tube wall: psuedostratified epi
Late neural tube: stratified epi

Question 3

What is the importance of the orientation of metaphase plate during proliferation of cells within the neural tube.

Answer 3

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

Question 4

Describe the heirarchy of basic cell lineages in development of nervous system, Also when mitosis cease in lineage and differentiation begins

Answer 4

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

Question 5

What is the effect of the graft secondary notochord near neural tube?

Answer 5

Induces a secondary floor plate

Question 6

What is the effect of removing the notochord?

Answer 6

The spinal cord is disorganized and has multiple exit sites of nerves

Question 7

What is the effect of slitting neural plate on one side of the floor plate?

Answer 7

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

Question 8

What is the signaling pathway and factors that establish the dorsal ventral axis of developing neural tube

Answer 8

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)

Question 9

What roles do the notochord and non nervous ectoderm play?

Answer 9

d

Question 10

Cranial nerve 5 relationship to rhombomeres and pharyngeal arches?

Answer 10

CN V is equivalent to rhombomere 2 in birds and innervates structures derived from first pharyngeal arch

Question 11

Cranial nerve VII relationship to rhombomeres and pharyngeal arches?

Answer 11

equivalent to rhombomere 4 in birds innervates structures derived from second pharyngeal arch

Question 12

CN IX relationship to rhombomeres and pharyngeal arches?

Answer 12

Equivalent to rhombomere 6 in birds innervates structures from third pharyngeal arch

Question 13

How is the segmented nature of spinal nerves related to somitic mesoderm pattern?

Answer 13

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.

Question 14

what is the role of isthmic organizer and what signaling TF are involved?

Answer 14

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.

Question 15

How does shh determine midbrain dorsoventral axis?

Answer 15

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.

Question 16

What role do prosomeres P1-P3 play in forebrain patterning?

Answer 16

Forebrain segmentation is represented by it. P1-P3 defines diencephalon and P2-P3 defines dorsal and ventral thalamus

Question 17

Refer to text for relation between Shh and holoprosencephaly?

Answer 17

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.

Question 18

Describe steps in outgrowth of motor neuron?

Answer 18

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

Question 19

List cues involved in axon guidance.

Answer 19

Caudal half of somite, Fibronectin and laminin, integrins and cadherins

Question 20

What are pioneering axons?

Answer 20

In periphreal nerves one pioneering axons is the axon that precedes the others in growth towards the target

Question 21

Describe steps in formation of synaptic junction.

Answer 21

1. Halting of axonal extension
2. Induction of synaptic vesicles releases sites
3. Synaptic release of ACh
4. Accumulation of Acetylcholinesterase
5. cluster of Ach receptors
6. elimination of nonjunctional ACh receptros
7. Formation of postynaptic folds

Question 22

What role does apoptosis play in establishment of neurite and end organ connections?

Answer 22

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.

Question 23

Describe steps in origin of sympathetic preganglionic neurons compare with parasympathetic preganglionic neurons.

Answer 23

Sympathetic preg. motor neurons come from lateral horns of grey mater.

Parasympathetic preg. come from midbrain, hindbrain, and S2-S4

Question 24

What factors determine whether migrating neural crest cells differentiate into autonomic neurons or other neural crest derivatives?

Answer 24

BMP’s determine this

Question 25

Cholinergic differentiation factor.

Answer 25

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.

Question 26

Hirschsprung’s disease?

Answer 26

Newborn with complete constipation w/o physical obstruction it is usually absence of parasympathetic ganglia from sigmoid colon and rectum

Question 27

What structure develops from the diencephaon?

Answer 27

Epithalamus
Thalamus
Hypothalamus
Infundibulum

Question 28

What structure develops from the mesencehpaon?

Answer 28

tectum, tegmentum, cerebral peduncles

Question 29

What develops from the metecephalon?

Answer 29

cerebellum and pons

Question 30

What develops from the myelencephaon?

Answer 30

Medulla

Question 31

What develops from the prosencephalon?

Answer 31

telencephalon and diencephalon

Question 32

What develops from the mesencephaon?

Answer 32

Mesencephalon

Question 33

What develops from the rhombencephalon?

Answer 33

Metencephalon and myelencephalon

Question 34

What role do netrins and semaphorins play?

Answer 34

Netrins are attractant and semaphorins are repulsive

Question 35

What are boundary caps and what role do they play in axon growth?

Answer 35

Boundary caps are created by neural crest cells to maintain separation between CNS and PNS

Question 36

What are growth cones??

Answer 36

expanded region of cytoplasm with filopodia they advance through extension/resporption cycles involving actin microfilaments