Neurodevelopment Flashcards

1
Q

When is neurulation initiated?

A

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

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2
Q

What does the ectoderm divide into (neurulation)?

A

The neural crest, neural tube, and epidermis.

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3
Q

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

A

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

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4
Q

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

A

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

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5
Q

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

A

Caudally: Spinal Bifida; Rostrally: Anencephaly.

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6
Q

Holoprosencephaly?

A

Disrupted forebrain development

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7
Q

Medulloblastoma?

A

Childhood tumor.

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8
Q

Significance of folic acid/vitamin A?

A

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

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9
Q

Where does the neural crest originate from?

A

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

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10
Q

What do neural crest cells differentiate into (3)?

A

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

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11
Q

Hirschprung’s disease?

A

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

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12
Q

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

A

Cranial facial disorders, pigment disorders, neurofibromatosis.

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13
Q

Neural tube differentiates into:

A

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

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14
Q

Forebrain (prosencephalon) differentiates into:

A

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

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15
Q

Midbrain (mesencephalon) differentiates into:

A

Superior and inferior colliculi

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16
Q

Hindbrain (rhombencephalon) differentiates into:

A

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

17
Q

When is segmentation detected in mammals?

A

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

18
Q

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

A

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)

19
Q

Molecular control of neurogenesis and gliogenesis involves:

A

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

20
Q

Migration Facts: Neural Crest Cells vs. Neurons

A

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

21
Q

Migration: inhibitory vs. excitatory neurons (cerebral cortex)

A

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.

22
Q

Describe the structure of the growth cone.

A

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.

23
Q

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

A

It must contact the signal molecule

24
Q

Netrin

A

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

25
Q

Commissural growth cones are attracted to:

A

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

26
Q

Main example of short range repellants.

A

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)

27
Q

Example of short range attractants:

A

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

28
Q

Name two important molecules in synapse formation.

A

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

29
Q

Postsynaptic density

A

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

30
Q

Trophic factors

A

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.

31
Q

Neurotrophins (neurotrophic factors)

A

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

32
Q

Embryonic stem cells

A

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

33
Q

Two regions that have neurogenesis occurring through adulthood.

A

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