Nervous System Embryology (objectives as they appear on blackbag) (not finished)

Question 1

Describe the normal development of the neural tube.

Answer 1

Neurulation begins at approximately day 18/19, i.e. near end of Wk 3.

1. Neuroectoderm thickens under inductive influence of notochord to form neural plate
2. Edges of neuroectoderm become elevated to form neural folds. The depression along the length of the midline is the neural groove.

Fusion begins in the region of the 5th somite (cervical region) very early in Wk 4. Fusion proceeds in cranially and caudally at the same time.
b. Rostral and caudal neuropores are the open ends of the neural tube, which communicate with the amniotic fluid. The space within the tube is the neural canal.
Rostral closes about day 24; Caudal closes about day 26

Neural tube will form the brain and spinal cord, i.e. the central nervous system (CNS)

1. Rostral to the 4th pair of somites → Brain
2. Caudal to the 4th pair of somites → Spinal Cord

Question 2

List the adult derivatives of the primary and secondary brain vesicles.

Answer 2

slide 18 depicts this really well

Question 3

What is the clinical significance of failure of the neuropores to close?

Answer 3

Failure of the neuropores to close properly can be coupled with ossification defects of the skull and vertebral column as development of the vertebral arch and skull are dependent on signals from the developing neural tube. This results in severe abnormalities of the brain and spinal cord.

Question 4

Describe the formation of the spinal cord from the neural tube.

Answer 4

a

Question 5

What is the relationship of the basal and alar plates to the overall organization of the spinal cord and brain?

Answer 5

The sulcus limitans is a longitudinal groove that lies along the inner lateral aspect of the neural tube. It marks the boundary between alar and basal regions of the neural tube. Neuroblasts in the alar plate develop into secondary (second order) sensory neurons; neuroblasts in the basal plate develop into motor neurons.

Question 6

Describe the development of the ventricular system.

Answer 6

a

Question 7

What makes up the choroid plexus? What are its embryologic origins?

Answer 7

a

Question 8

What kinds of symptoms would you expect to find in a patient with abnormal development of the neural crest?

Answer 8

a

Question 9

Describe how the organization of the cranial nerve nuclei and fibers mirrors that of the spinal cord.

Answer 9

a

Question 10

Describe the development of the hypophysis (pituitary gland).

Answer 10

a

Question 11

Explain the developmental origins of these congenital malformations or diseases:
spina bifida occulta

Answer 11

a

Question 12

Explain the developmental origins of these congenital malformations or diseases:
spina bifida cystica (meningocele, meningomylocele)

Answer 12

a

Question 13

Explain the developmental origins of these congenital malformations or diseases:
anencephaly/merocephaly

Answer 13

a

Question 14

Explain the developmental origins of these congenital malformations or diseases:
Arnold-Chiari malformation

Answer 14

a

Question 15

Explain the developmental origins of these congenital malformations or diseases:
syringomelia, hydromyelia

Answer 15

a

Question 16

Explain the developmental origins of these congenital malformations or diseases:
hydrocephalus

Answer 16

a

Question 17

Explain the developmental origins of these congenital malformations or diseases:
Hirschsprung disease (congenital megacolon)

Answer 17

a

Question 18

Explain the developmental origins of these congenital malformations or diseases:
Waardenburg syndrome

Answer 18

a

Question 19

Describe the normal development of the neural crest (neurulation)

Answer 19

. Neural Crest Cells are motile neuroectodermal cells lie dorsal and lateral to the neural tube. They migrate throughout the embryo developing into many structures that seem unrelated to one another. (MP&T fig 17-8)

a. Neural crest will form the peripheral nervous system (PNS) including:
1. Most sensory neurons in the spinal and cranial ganglia
2. Autonomic ganglia
3. Enteric ganglia and nerves
4. Schwann cells
5. Satellite cells
and

b. A wide variety of non-neural structures (this list is not complete)
6. Arachnoid and pia mater
7. Connective tissues of the aorta
8. Merkel cells-pressure sensitive cells in skin
9. Chromaffin cells of adrenal medulla that secrete adrenaline (epinephrine)
10. Odontoblasts
11. Various cartilages and bones of the head and neck
12. Melanocytes

Question 20

Describe the normal development of the neural crest (neurulation)

Answer 20

. Neural Crest Cells are motile neuroectodermal cells lie dorsal and lateral to the neural tube. They migrate throughout the embryo developing into many structures that seem unrelated to one another. (MP&T fig 17-8)

a. Neural crest will form the peripheral nervous system (PNS) including:
1. Most sensory neurons in the spinal and cranial ganglia
2. Autonomic ganglia
3. Enteric ganglia and nerves
4. Schwann cells
5. Satellite cells
and

b. A wide variety of non-neural structures (this list is not complete)
6. Arachnoid and pia mater
7. Connective tissues of the aorta
8. Merkel cells-pressure sensitive cells in skin
9. Chromaffin cells of adrenal medulla that secrete adrenaline (epinephrine)
10. Odontoblasts
11. Various cartilages and bones of the head and neck
12. Melanocytes

Question 21

Describe the normal development of the neural crest (neurulation)

Answer 21

. Neural Crest Cells are motile neuroectodermal cells lie dorsal and lateral to the neural tube. They migrate throughout the embryo developing into many structures that seem unrelated to one another. (MP&T fig 17-8)

a. Neural crest will form the peripheral nervous system (PNS) including:
1. Most sensory neurons in the spinal and cranial ganglia
2. Autonomic ganglia
3. Enteric ganglia and nerves
4. Schwann cells
5. Satellite cells
and

b. A wide variety of non-neural structures (this list is not complete)
6. Arachnoid and pia mater
7. Connective tissues of the aorta
8. Merkel cells-pressure sensitive cells in skin
9. Chromaffin cells of adrenal medulla that secrete adrenaline (epinephrine)
10. Odontoblasts
11. Various cartilages and bones of the head and neck
12. Melanocytes