Lecture 6: Development of CNS

Question 1

When does fertilization occur?

Answer 1

When sperm meets oocyte forming zygote

Question 2

What is the cell division process?

Answer 2

Zygote become morula (16 cells) which then becomes a blastula

Question 3

What begins after formation of a blastula?

Answer 3

Gastrulation begins

Question 4

What is the blastopore?

Answer 4

Initial site of invagination

Question 5

What does the invagination of a single sheet of cells produce?

Answer 5

3 germ layers: ectoderm, mesoderm, endoderm

Question 6

What is defined in gastrulation?

Answer 6

Spatial orientation of the embryo

Question 7

What is the notocord formed as?

Answer 7

A cylinder of mesodermal cells defining midline

Question 8

What does the notocord formation signal?

Answer 8

The overlying ectoderm to become neuroectoderm

Question 9

What is the CNS derived from?

Answer 9

Neuroectoderm

Question 10

What happens to the neuroectoderm as development progresses?

Answer 10

It invaginates

Question 11

What happens to lateral margins?

Answer 11

Also known as neural folds, they fuse along midline forming neural tube, and internally, the neural canal

Question 12

What is at the junction of the ectoderm and neuroectoderm?

Answer 12

A layer of ectodermal epithelial cells (neural crest cells) that separates as the neural tube is formed

Question 13

Where does initial closure begin? Where does it progress?

Answer 13

Begins at rhombencephalon and progresses rostrally and caudally

Question 14

What may persist after closure?

Answer 14

A small opening may persist caudally maintaining communication of the subarachnoid space with conus medullaris

Question 15

What 3 vesicles develop during closure?

Answer 15

Prosencephlaon
Mesencephalon
Rhombencephalon

Question 16

What does the prosencephalon form?

Answer 16

Cerebral hemispheres (which contain telencephalon vesicles)
Diencephalon, which is the rostral aspect of the neural tube (contains optic vesicles)

Question 17

What does the notochord secrete?

Answer 17

Sonic Hedge hog

Question 18

What does sonic hedge hog do?

Answer 18

Stimulates motor neuron development

Question 19

What cell layer does the neural tube develop from?

Answer 19

Ectoderm/neuroectoderm

Question 20

What are the 4 neurologic features that develop from the neural crest cells?

Answer 20

Dorsal root ganglia
Post ganglionic neurons of ANS
Leptomeninges
Schwann cells

Question 21

What are the 3 vesicles that form the brain?

Answer 21

Prosencephalon
Mesencephalon
Rhombencephalon

Question 22

What does the prosencephalon form?

Answer 22

Telencephalon (cerebrum)

Question 23

What does the mesencephalon form?

Answer 23

Mesencephalon (midbrain)

Question 24

What does the rhombencephalon form?

Answer 24

Metencephalon (pons and cerebellum)

Myelencephalon (medulla)

Question 25

What is found in the germinal layer?

Answer 25

Ependymal cells

Question 26

What is found in the mantle layers?

Answer 26

Gray matter

Question 27

Where is gray matter located in the spinal cord?

Answer 27

Central to the white matter

Question 28

Where is gray matter located in the cerebral cortex and cerebellum?

Answer 28

Peripheral to the white matter

Question 29

What is found in the marginal layer?

Answer 29

White matter