Lecture 10 - Neurogenesis and Migration I

Question 1

Pleiotropy

Answer 1

genes with more than one function

Question 2

examples of pleiotropy

Answer 2

BMP, Shh (floor plate, motor neurons, eye cups)

Question 3

Redundancy

Answer 3

multiple genes do same function

Question 4

redundancy examples

Answer 4

noggin, chordin, follistatin (neural plate differentiation

Question 5

Haploid cells

Answer 5

with half the individual genes

Question 6

lumen

Answer 6

center of ventricular zone

Question 7

mitotic figures

Answer 7

the tangled threads of duplicated chromosomes being pulled apart that seen in cell undergoing mitosis

Question 8

location of mitotic figures

Answer 8

closest to lumen, never on plial surface

Question 9

plial surface

Answer 9

outer surface of lumen, set boundary of brains ventricles

Question 10

lumen becomes….

Answer 10

ventricles/ventricular surface

Question 11

central cavity within neural tube becomes…

Answer 11

the ventricles of the brain and central canal of the spinal cord

Question 12

meninges

Answer 12

three layers of tissue protecting the vertebrate CNS

Question 13

pia mater

Answer 13

innermost layer of the vertebrate meninges, found along the outer surface of the brain

Question 14

ventricular zone

Answer 14

the regions adjacent to the ventricles of the brain and central canal of the spinal cord, where cell division continues throughout life

Question 15

neuroblast

Answer 15

a cell that will divide to produce neural cells

Question 16

stretching of cells

Answer 16

neural tube starts as 1 cell thick, as it grows, cells retain their connection to both surfaces

Question 17

display of mitotic figures

Answer 17

as neuroblasts are dividing, their nuclei shuttle back and forth within the cytoplasm, from the ventricular surface to plial surface, displaying mitotic figures only when close to ventricular surface

Question 18

symmetrical cell division

Answer 18

neuroblast divides to produce 2 neuroblasts that are still attached across the width of the tube

Question 19

asymmetrical cell divsion

Answer 19

a neuroblast divides so one cell remains attached to the ventricular and plial surfaces and prepares to divide again, while the other daughter cell has no attachment to either surface and migrates away from the ventricular zone

Question 20

stretched cells become

Answer 20

radial glia

Question 21

layer 1

Answer 21

first postmitotic cortical cells settle in the outermost marginal zone

Question 22

cells that don’t settle

Answer 22

release their hold on the plial surface and stay on the ventricular zone, capable of mitosis throughout life

Question 23

germinal zone

Answer 23

ventricular zone

Question 24

neurogenesis

Answer 24

process of dividing to produce cells that differentiate into neurons

Question 25

gliogenesis

Answer 25

production of new glia; happens throughout life

Question 26

later arriving cells

Answer 26

form just beneath the marginal zone to form the other 5 layers of cortex

Question 27

intermediate zone will become...

Answer 27

the region filled with axons coming and going from the cortex

Question 28

GFAP

Answer 28

a structural protein normally expressed in radial glia and astrocytes but not in neurons; a proportion of cells in the cortical ventricular zone express

Question 29

question of cloning experiment

Answer 29

do dividing cells start narrowing in on cell fates, each producing progeny that all develop into only one particular type of cell (neurons, astrocyte, oligodendrocyte)

Question 30

hypothesis

Answer 30

all progeny produced by the final few rounds of mitosis will be alike, either all neurons or all astrocytes or all oligodendrocytes

Question 31

test

Answer 31

infected cells that were in final divisions with virus into genome to incorporate LacZ - a reporter gene because its product will report to us which cell descended from original infected cell (b-gal light blue)

Question 32

result

Answer 32

no relationship among cells produced by infected cells

Question 33

conclusion

Answer 33

no pattern of offspring from single infected cell; no evidence that neural cells in final stages of mitosis are becoming specified (remain multipotent, capable of producing progeny that pursue a variety of fates)

Question 34

cerebellum cell layers

Answer 34

external granular layer, purkinje cells, internal granular layer

Question 35

external granule layer

Answer 35

a layer of granule neurons that migrate to the top of the developing cerebellum before migrating ventrally to form the internal granule cell layer in adulthood; next to outside of marginal zone

Question 36

purkinje cells

Answer 36

large, multipolar neurons form a single layer, flanked by the external and internal granular layer

Question 37

internal granular layer

Answer 37

a layer of small neuons ventral to the purkinje cell layer in the vertebrate cerebellar cortex, located next to the intermediate zone

Question 38

subventricular zone

Answer 38

the region just next to the ventricular zone, where many cells divide (neuroblast) to provide neurons and glia to the developing vertebrate brain and new neurons in adulthood

Question 39

proliferative zone

Answer 39

ventricular zone and SVZ are together

Question 40

cell division in SVZ vs. ventricular zone

Answer 40

asymmetrical ventricular zone, symmetrical SVZ

Question 41

ventricular zone shrinks to form...

Answer 41

ependyml layer that lines the cerebral ventricles

Question 42

intermediate zone (white matter)

Answer 42

very little cell bodies, fills with axons that form the inner white matter of the brain upon myelination

Question 43

cortical plate

Answer 43

neurons and glia accumulate, forming grey matter; expanding layer of postmitotic cells that settle beneath the marginal zone and above the intermediate zone (layers II-VI)

Question 44

gray matter

Answer 44

outer portion of vertebrate brain, predominated by neuronal and glial cell bodies rather than myelin, hence dark in color in postmortem preparations (6 layers)

Question 45

molecular layer

Answer 45

no cell bodies, outermost layer of cortex, consisting primarily of dendrites and axons, located immediately next to pia

Question 46

layer 1 formed by

Answer 46

molecular layer and marginal zone