Development of the Nervous System

Question 1

Name 3 molecules that inhibit BMP.

Answer 1

Chordin, Noggin, Follistatin

Question 2

What does mesoderm inhibit to induce nervous differentiation in the ectoderm?

Answer 2

BMP

Question 3

In what direction does the neural tube close?

Answer 3

Cranial to caudal

Question 4

Name the 5 secondary vesicles and the primary vesicles from which they come.

Answer 4

Telencephalon & diencephalon from forebrain. Mesencephalon from midbrain. Metencephalon and myelencephalon from hindbrain.

Question 5

Which secondary vesicle do the olfactory lobes, hippocampus, and cerebrum come from?

Answer 5

Telencephalon

Question 6

Which secondary vesicle do the retina, epithalamus, thalamus, and epithalamus come from?

Answer 6

Diencephalon

Question 7

Which secondary vesicle does the midbrain come from?

Answer 7

Mesencephalon

Question 8

Which secondary vesicle does the cerebellum and pons come from?

Answer 8

Metencephalon

Question 9

Which secondary vesicle does the medulla come from?

Answer 9

Myelencephalon

Question 10

What gene can you knock out to cause anencephaly in mice? (specifically, no formation of all anterior neural structures)

Answer 10

otx2

Question 11

What transcription factors repress each other in the telencephalon (forebrain)? Which one is expressed anteriorly? What promotes its expression

Answer 11

Pax6 and Emx2. Pax6 is expressed anteriorly and is promoted by FGF8.

Question 12

What division of the brain has rhombomeres during development?

Answer 12

the hindbrain

Question 13

What’s the significance of the order of Hox genes on the chromosome?

Answer 13

Order on the chromosome recapitulates cranial-caudal sequence of gene expression.

Question 14

Which two factors are most important in determining the dorsal-ventral axis of the neural tube? Which does which?

Answer 14

Shh (ventrally from the notochord) and BMP (dorsally from ectoderm).

Question 15

What is holoprosencephaly? What’s one way is happens?

Answer 15

Defect of bifurcation of forebrain into two lobes -> single holosphere. Can happen due to loss of Shh signaling components.

Question 16

Describe the intrinsic lineage mechanism for differentiation.

Answer 16

Factors within the progenitor cell are unevenly divided among the cell’s progeny, and these factors determine the progeny’s fate. (the “European” way - less social mobility…..)

Question 17

Describe the extrinsic mechanism for cell differentiation.

Answer 17

Extrinsic factors act on the progeny of a progenitor cell to determine its fate. (the “American” way -more social mobility…. but not actually)

Question 18

What do the majority of neural crest cells below the neck do? Name 4 specific things.

Answer 18

Peripheral nervous system: Sensory ganglia, autonomic ganglia, and adrenal neuro-secretory ganglia. Also non-neuronal melanocytes.

Question 19

Do neural crest cells differentiated by an intrinsic or extrinsic mechanism?

Answer 19

Extrinsic, due to local signaling molecules, as is illustrated by chick-quail transplant studies.

Question 20

What’s an experiment that showed puripotency of progenitor cells in the CN (specifically in the retina).

Answer 20

Progenitor cell injected with virus. Cells of various types that had come from the same clone could be identified based on the presence of the virus.

Question 21

Where is the proliferative zone in the cortex for excitatory neurons? (ie. which side are the progenitors on, ventricular or pial?)

Answer 21

Ventricular. Excitatory neurons have “inside-out” development.

Question 22

Where are inhibitory GABAnergic neurons in the cortex generated? What happens if these fail to develop?

Answer 22

The ventral telencephalon. Without them, people lack inhibitory interneurons and get epilepsy.

Question 23

What is lissencephaly? What gene defect can cause it?

Answer 23

Smooth brain - lack of gyri and sulci. Loss of Lis1 can cause lissencephaly.

Question 24

What does Doublecortin (dcx) do?

Answer 24

It’s a microtubule-associated protein (MAP) needed for neuron migration

Question 25

What is the growth cone?

Answer 25

The motile structure at the tip of the neuron.

Question 26

What are 3 types of signals that can guide axon migration?

Answer 26

Chemorepulsion, chemoattraction, and contact attraction.

Question 27

What axon-guidance factor directs the crossing of interneuron axons, given as an example in lecture (for fish tickling, and human eye coordination)

Answer 27

robo-3

Question 28

What do Sperry’s frog experiments on eyes tell you about axon regeneration?

Answer 28

Retinal fibers regenerated to their original positions in the tectum, not to what’s closest, frustrating their efforts to catch flies.

Question 29

What axon attractants/repellents set up the anterior-posterior axis in the optic tectum? Which ones set up the dorsal-ventral axis?

Answer 29

A-P: Ephrin As (mnemonic: A is for Anterior-posterior)

D-V: Ephrin Bs

Question 30

More neurons are born than become functional. What’s a family of signaling molecule that promotes the survival of specific neurons?

Answer 30

Neurotrophins

Question 31

What trophic factor allows pre-synaptic sympathetic nerves to survive? What cell makes it?

Answer 31

Nerve Growth Factor (NGF), made by post-synaptic sympathetic cells (the target of the migrating axons)