Nervous System Development II

Question 1

What happens to the pineal cord around the 11th week of gestation?

Answer 1

• It begins to REGRESS form the CAUDAL portion of the spinal cord
• This forms the CAUDA EQUINA

Question 2

What does the regression of the spinal cord provide?

Answer 2

A safe place to withdraw CSF

Question 3

Spinal cord gray matter organization

Answer 3

• Central
• Ant./Post./Lat. Horns
• Horns situated around a Central canal

Question 4

Brain gray matter organization

Answer 4

Deep areas are rep. By the Basal Nuclei and other nuclear groups

Question 5

Brain white matter organization

Answer 5

Myelinated FIBER Tracts throughout various parts of the brain

Lie superficial to the gray matter

Question 6

T/F: in the Cerebrum and Cerebellum, additional EXTERNAL areas of Gray matter (The Cortices) are built on top of (External to) the myelinated white matter.

Answer 6

True

Question 7

Classical Def of a Cerebral Cortex

Answer 7

• Multiple Layers of gray matter (6)
• Built from the INSIDE OUT
• Most superficial layer added last

Question 8

Exceptions to the Cortex growth rule

Answer 8

• Neuronal Migration
  (Parallel)
• Cerebellar/Cerebral cortices have only 3 layers
• Some parts of the cerebral cortex are built from the Outside IN

Question 9

Role of Radial GLIAL cells in the building of a cortex

Answer 9

• Extends long process that passes through the

1. Intermediate Zone
2. Cortical Plate
3. Marginal Zone (Outermost)

To the SURFACE Of the brain

Question 10

*The topographical arrangement of the Myelen-Cephalon is almost identical to the spinal cord.

What is the MAJOR Topographical change?*

Answer 10

• Pronounced expansion of the ROOF PLTE

- To form the thin roof over the FOURTH ventricle

Question 11

Expression of which set of genes seems to be responsible for the differentiation of Specific nuclei in the Myelen-Cephalon?

Answer 11

Hox genes

Question 12

What are the major derivatives of the Meten-Cephalon?

Answer 12

• Pons (Basal plate)

- Cerebellum (Alar plate)

Question 13

*The Cerebellum forms in the region of the RHOMBIC Lips (1-8). The lips are the product of what Inductive Interaction?

Answer 13

Roof plate and Neural Tube via BMP Signaling

Question 14

*Migration of cells that will for the Cortex in the Cerebellar Primordium *

Answer 14

1. Granule cells Migrate ANTERIORLY along dorsal region of Rhombomere 1
2. Then Migrate INTERIORLY through Purkinje layer
3. Purkinje cells Migrate RADIALLY through Granular cells

Question 15

What are the Superior Cerebellar Peduncles?

Answer 15

Massive FIBER bundles b/w the Cerebellum and the MESEN-Cephalon

Question 16

What are the Major derivatives of the ALAR plate of the Mesencephalon?

Answer 16

Tectum (Corpora Quadrigemina)

- Sup/Inf Colliculi

Question 17

Where is Oti-2 located and how is it related to SHH?

Answer 17

Confines SHH to the BASAL part of the MIDBRAIN

Question 18

Where do the Cerebral Peduncles form and what is their fxn?

Answer 18

1. Ventro-Lateral region of the MESEN-Cephalon

2. Carry fibers b/w the Cerebral HEMISPHERES and the Spinal Cord

Question 19

• What are the Major derivatives of the Diencephalon?*

Answer 19

• Epithalamus
• Thalamus
• Hypothalamus

Question 20

What are the THREE Patterning centers in the Forebrain?

Answer 20

1. Rostral (FGF-8)
2. Dorsal (BMPs and Wnts)
3. Ventral (SHH)

Question 21

How many Cranial nerves are there?

Answer 21

12

Question 22

Why are CN I and II not True Nerves?

Answer 22

They Do not join with the BRAINSTEM

Question 23

What is Rachischisis?

Answer 23

• The brain is NOT covered by cranial bones

- The spinal cord is totally exposed