Development of the Nervous System

Question 1

Origin of the Nervous System

Answer 1

arises 3rd week of embryonic life when ectoderm, endoderm, and mesoderm are generated

Question 2

Ectoderm

Answer 2

outermost layer
Ex. skin, nervous system

Question 3

Mesoderm

Answer 3

middle developmental layer
Ex. skeleton, muscles, heart, bone

Question 4

Endoderm

Answer 4

Innermost layer
Ex. forms lining of respiratory & GI tract

Question 5

Gastrulation

Answer 5

outer cells (epiblast) of embryo detach and migrate thru primitive streak - creates endoderm and mesoderm
epiblast forms ectoderm

Question 6

Neural Induction

Answer 6

invagination of early embryonic ectoderm, forming neural tube

Question 7

How does the neural tube close?

Answer 7

anterior and posterior neuropores close
zip toward the head and tail

Question 8

Notochord

Answer 8

involved in ventral patterning
becomes incorporated in the developing intervertebral disks of skeleton

Question 9

Somites

Answer 9

form most of the vertebral column and segmental units of muscle (myotomes) and dermis (dermatomes)

Question 10

Craniorachischisis

Answer 10

open spinal cord and spine
CNS is abnormally open on its dorsal surface

Question 11

Anencephaly

Answer 11

failure of the rostral end of the neural tube
to close

Question 12

Spina bifida

Answer 12

failure of the caudal end of the neural tube
to close

Question 13

Primary Brain Vesicles

Answer 13

bulges and kinks appear along the anterior-posterior extent of the neural tube (prosencephalon, mesencephalon, rhombencephalon)

Question 14

Secondary Brain Vesicles

Answer 14

prosencephalon (forebrain) - telencephalon & diencephalon
mesencephalon (midbrain)
rhombencephalon (hindbrain) - metencephalon & myelencephalon

Question 15

Derivatives of Secondary Vesicles

Answer 15

telencephalon - cerebrum
diencephalon - thalamus, hypothalamus, retina, midbrain structures
mesencephalon - midbrain
metencephalon - pons, cerebellum
myelencephalon - medulla

Question 16

What are neural crest cells and what do they give rise to?

Answer 16

transient migratory group of cells that give rise to sensory neurons (posterior root ganglia of spinal nerves, some cranial nerves), all post-ganglionic neurons of the autonomic nervous system, the adrenal medulla and Schwann cells

Question 17

How are neural crest cells produced?

Answer 17

As the neural tube separates from the ectoderm it leaves behind a group of cells that were at the crest of each neural fold