Neurodevelopment

Question 1

When is neurulation initiated?

Answer 1

When the mesoderm (notochord) sends a message to the ectoderm

Question 2

What does the ectoderm divide into (neurulation)?

Answer 2

The neural crest, neural tube, and epidermis.

Question 3

What is the ventricular zone and what does it give rise to?

Answer 3

Cells in the neural tube; gives rise to oligodendrocytes, neurons, and astrocytes (also contains dividing neuroectodermal cells).

Question 4

Six signals that play a role during neural induction by modulating gene expression:

Answer 4

Wnt, BMD, shh, retinoic acid, and fibroblast growth factor,

Question 5

Failure of neural tube closure (caudal and rostral ends) is called?

Answer 5

Caudally: Spinal Bifida; Rostrally: Anencephaly.

Question 6

Holoprosencephaly?

Answer 6

Disrupted forebrain development

Question 7

Medulloblastoma?

Answer 7

Childhood tumor.

Question 8

Significance of folic acid/vitamin A?

Answer 8

Folic acid: given to pregnant women to decrease the incident of neural tube closure defects. Vitamin A: causes tube closure disruption in excess.

Question 9

Where does the neural crest originate from?

Answer 9

The dorsal most neural tube (cranial to lumbar regions).

Question 10

What do neural crest cells differentiate into (3)?

Answer 10

Neurons and glia (PNS); neuroendocrine cells in the adrenal medulla; non-neural cells (melanocytes/cartilage and bone (face), outflow tract in the heart).

Question 11

Hirschprung’s disease?

Answer 11

Defect of migration of neural crest cells to the colon (loss of enteric neurons in the colon)

Question 12

Three neural crest disorders (not including Hirschprung’s).

Answer 12

Cranial facial disorders, pigment disorders, neurofibromatosis.

Question 13

Neural tube differentiates into:

Answer 13

Forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon), caudal tube (spinal cord)

Question 14

Forebrain (prosencephalon) differentiates into:

Answer 14

Telencephalon (cerebral cortex, hippocampus, basal ganglia, basal forebrain nuclei, olfactory bulb), diencephalon (thalamus, hypothalamus, retina)

Question 15

Midbrain (mesencephalon) differentiates into:

Answer 15

Superior and inferior colliculi

Question 16

Hindbrain (rhombencephalon) differentiates into:

Answer 16

Metencephalon (pons, cerebellum), mesencephalon (medulla oblongata)

Question 17

When is segmentation detected in mammals?

Answer 17

During hindbrain development (rhombomeres), lead by the Hox gene.

Question 18

Progenitor cells in the ventricular zones are…? (also order of generation)

Answer 18

They are mitotically active and generate into neurons first, oligodendrocytes second, and astrocytes last. (When they leave the ventricular zone they are no longer mitotically active)

Question 19

Molecular control of neurogenesis and gliogenesis involves:

Answer 19

Notch signaling and bHLH transcription factors (problems often lead to tumors: glioblastomas, medulloblastomas)

Question 20

Migration Facts: Neural Crest Cells vs. Neurons

Answer 20

Neural crest cells are guided via adhesion molecules in the ECM, Neurons migrate along radial glia processes.

Question 21

Migration: inhibitory vs. excitatory neurons (cerebral cortex)

Answer 21

Excitatory neurons originate in the dorsal telencephalon and are organized in layers. Inhibitory neurons have a different origin (ventrally) and travel far dorsally to the developing cortex.

Question 22

Describe the structure of the growth cone.

Answer 22

Edge has numerous protrusions called filopodia (actin filaments, dynamic movements, respond to chemical environments). THe center of the growth cone is made up of microtubules.

Question 23

A filopodium must do what to respond to a signal molecule?

Answer 23

It must contact the signal molecule

Question 24

Netrin

Answer 24

Major long-range attractant (also can be a repellant!!)

Question 25

Commissural growth cones are attracted to:

Answer 25

netrin secreted the floor plate (after crossing the surface receptors on the cone change to ones REPELLED by netrin).

Question 26

Main example of short range repellants.

Answer 26

Ephrins: retina growth cones localize to certain parts of the tectum. This is achieved by axons from the temporal retina having receptors (or not having receptors) for ephrin ( a repellant)

Question 27

Example of short range attractants:

Answer 27

Fasciculation: CAMs that allow for axon-axon communication and bundle growth (also the basis for pioneer neurons - think ants; regeneration)

Question 28

Name two important molecules in synapse formation.

Answer 28

Neurexin (pre-synaptic), Neuroligin (post-synaptic). Mutations in these molecules is associated with Autism

Question 29

Postsynaptic density

Answer 29

Specialized intercellular junction that localizes neurotransmitter receptors and other molecules important for neuronal transmission.

Question 30

Trophic factors

Answer 30

Sustain the life of neurons, control the number and shape of synapses on a target (also important are neurotrophins and electrical activity). Trophic factors are responsible for the shape of the ventral horn of the spinal cord.

Question 31

Neurotrophins (neurotrophic factors)

Answer 31

NGF, BDNF, NT3, NT4. Bind to growth cone receptors with prefix Trk (each Trk has a specificity to one neurotrophic factor)

Question 32

Embryonic stem cells

Answer 32

pluripotent cells that can give rise to every cell type in the organism

Question 33

Two regions that have neurogenesis occurring through adulthood.

Answer 33

Subventricular zone of the lateral ventricles (olfactory bulb nurons), subgranular layer in the dentate gyrus of the hippocampus (granule neurons).