Neurogenesis and axon guidance

Question 1

developing telencephalon

Answer 1

ventricular zone: contains radial glia which migrate radially to form excitatory neurons in the cortex

medial ganglionnic eminance: contains stem sells which migrate laterally to form inhibitory neurons

Question 2

migration of radial glia in ventricular zone

Answer 2

as they divide, cell bodies move up and down

cells may divide vertically or horizontally as the ventricular surface

Question 3

division of radial glia cells

Answer 3

transcription factor profile determies cell identity

vertical division creates identical daughter cells (more stem cells)

horizontal division creates differentiated cells

Question 4

radial glia form

Answer 4

cortical neruons and astrocytes

Question 5

construction of cortex

Answer 5

“inside out”

Question 6

growth cones

Answer 6

tip of growing axon, have many finger like, actin rich projections called filopodia that explore the environment and have receptors that respond to guidance cues

Question 7

axon guidance cues

Answer 7

expressed in EC space

chemoattractants: molecules that attract a growing axon, netrin (its receptor is DDC)
chemorepellants: molecules that repel growing axon, slit (its receptor is robo)

receptors determine direction of axon growth

Question 8

intermediate targets

Answer 8

aka choice points, most have multiple cue types

Question 9

midline of spinal cord

Answer 9

an intermediate target for motor axons,

Question 10

axon growth in the absence of robo or DDC

Answer 10

no robo: motor axons circle the midline

no DDC: axons would remain ipsilateral, mirror movement disorder

Question 11

retinal ganglion cell axons

Answer 11

dorsal- contralateral

temporal- ipsilateral