Lecture 19 - Neurogenesis connectivity of cell death

Question 1

How does Proliferation and Cleavage occur?

Answer 1

1. A cell extends a process that reaches up toward the pial surface (in ventricular zone).
2. The nucleus move ups towards the pial surface and the cells’ DNA is copied (in marginal zone).
3. Nucleus with 2 copies of DNA moves back to ventricular surface (in marginal zone).
4. Cell retracts its arm from pial surface (in ventricular zone).
5. The cell divides and comes back down

Question 2

What is the difference between vertical cleavage and horizontal cleave?

Answer 2

Vertical cleave

• • Symmetric division. Both cells remain in ventricular zone. Gives rise to 2 stem cells. Leads to expanding population

Horizontal cleave

• • Asymmetric division. One cell remains in ventricular zone. one cell move up to form
    cortex. Leads to Differentiation

Question 3

How Does A Cell Decide its Cleavage Plane?

Answer 3

Based on the transcription factors during cell division determines the fate of the daughter cells

Question 4

What is significant about Notch-1 and Numb and cleavage planes?

Answer 4

• vertical cleavage plane of Notch and Numb lead to a symmetrical plane and Both cells end up with Notch-1 and Num are transcription factors
• horizontal cleavage of Notch and Numb lead to an asymmetrical plane. Notch-1 and Numb end up in 2 different cells. Which stops cell (when Notch-1 by itself) from dividing and making it differentiate

Question 5

Neural stem cells give rise to what

Answer 5

• neurons and glia

Question 6

What is the process of Cell Migration to Form a Cortical Plate?

Answer 6

• First cells to migrate take up residence in “subplate” layer which eventually disappears - starts formation of layers
• Next cells to divide migrate to the cortical plate
• The first to arrive become layer VI, followed V, IV, and so on: “inside out”

Question 7

How doe GABAergic interneurons migrate?

Answer 7

• migrate tangentially from lateral and medial ganglionic eminences (LGE, MGE) to the cortex

Question 8

How doe glutamatergic interneurons migrate?

Answer 8

• Generated locally in the cortical ventricular zone (pallium)
• migrate radially to form the cortex

Question 9

What is neuronal differentiation

Answer 9

Process where cells can take on appearance and characteristics of neurons.

Question 10

What are the Gradients of Emx2 and Pax6

Answer 10

Emx2 - more at the back of brain
Pax 6 - more at the front of brain

Question 11

What happens if a person is deficient in Emx2 or Pax6

Answer 11

Emx2 - bigger motor cortex and underdevelopment of other parts of brain
Pax6 - Bigger visual cortex but underdevelopment of other parts of the brain

Question 12

What are the 3 phases of pathway formation?

Answer 12

(1) pathway,
(2) target,
(3) address

Question 13

What is fasciculation

Answer 13

Axon grow together stick together with cell-adhesion molecules.

Question 14

What are laminin molecules?

Answer 14

allows axon to grab on and move forward together during cell migration

Question 15

What is the pioneer tract?

Answer 15

the very first axons to grow out to find their targets.
They often form a trail which other axons follow.

Question 16

What are two types of guidance clues?

Answer 16

chemoattractant and chemorepellent

Question 17

What is the process of guidance clues?

Answer 17

• Netrin and Slit are secreted by neurons in midline
• Gradient of Netrin attracts axons of dorsal horn that have netrin recepors expressed
• After decussation (axon cross midline) Axon reduce netrin receptor expression and begin to express robo (slit receptor)
• axon grows away from midline

Question 18

Nasal retina grow in what in topographic maps?

Answer 18

The anterior and posterior tectum due to low levels of receptors

Question 19

Temporal retina grow in what in topographic maps?

Answer 19

The anterior tectum due to High levels of receptor expressed in anterior tectum

Question 20

what are the Steps in the formation of a CNS synapse

Answer 20

1. Dendritic filopodium contacts axon
2. Synaptic vesicles and active zone proteins recruited to presynaptic membrane
3. Receptors accumulate on postsynaptic membrane

Question 21

List Trophic Factors

Answer 21

Endocrine - through CSF
Paracrine - from other cells
Autocrine - from the cell itself
Juxtacrine - receiving through direct- contact of another cell