Lecture 17

Question 1

What is the classical definition of a cortex?

Answer 1

true cortex consists of multiple layers of gray matter (six layers) and is built from the inside out, with the most superficial layers added last

Question 2

What are the exceptions to the cortex?

Answer 2

• neural migration in the building of the cerebellar cortex occurs parallel to the surface (rather than perpendicular)
• cerebellar cortex and some areas of the cerebral cortex consists of three layers
• some parts are built outside to inside

Question 3

What are the characteristics of radial glial cells?

Answer 3

located in ventricular (ependymal) zone
each one extends a long process that passes through the intermediate zone, cortical plate, and marginal zone to surface of brain

Question 4

The topographical arrangement of the myelencephalon is almost identical to the spinal cord. What is the major topographical change?

Answer 4

pronounced expansion of the roof plate to form the thin roof over the fourth ventricle

Question 5

Expression of which set of genes seems to be responsible for the differentiation of specific nuclei in the myelencephalon?

Answer 5

Hox genes

Question 6

What are the major derivatives of the mesencephalon?

Answer 6

pons (basal plate)

cerebellum (alar plate)

Question 7

The cerebellum forms in the region of the rhombic lips (rhombomeres 1-8). The rhombic lips are the product of what inductive interaction?

Answer 7

roof plate and neural tube via BMP signaling

Question 8

What is the cell migration that form the cortex in the cerebellar primordium?

Answer 8

• granule cells migrate anteriorly along dorsal region of rhombomere 1
• granule cells migrate interiorly through purkinje layer
• purkinje cells migrate radially through granule cells

Question 9

What are the superior cerebellar peduncles?

Answer 9

massive fiber bundles between the cerebellum and the mesencephalon

Question 10

What are the major derivatives of the alar plates of the mesencephalon?

Answer 10

tectum: superior and inferior colliculi

Question 11

Where is Otx-2 located and how is it related to shh?

Answer 11

confines Shh to the basal part of the midbrain

Question 12

Where do the cerebral peduncles form and what is their function?

Answer 12

ventrolateral region of the mesencephalon

carry fibers between the cerebral hemispheres and spinal cord

Question 13

What are the major derivatives of the diencephalon?

Answer 13

epithalamus, thalamus, hypothalamus

Question 14

What are the three pattern centers in the forebrain?

Answer 14

rostral patterning center (FGF-8)
dorsal patterning center (BMPs and Wnts)
ventral patterning center (Shh)

Question 15

What is Krox 20?

Answer 15

segmentation gene that is involved in the formation of rhombomeres 3 and 5