9. Neurulation & Neural Crest

Question 1

What develops during week 1?

Answer 1

Formation of the inner cell mass

Days 0-7

Question 2

What develops during week 2?

Answer 2

Formation of epiblast and hypoblast

Days 8-14

Question 3

What develops during week 3?

Answer 3

Gastrulation

Days 15-21

Question 4

What happens during days 6-10?

Answer 4

Implantation

Question 5

What are the 3 primary germ layers?

Answer 5

Ectoderm
Mesoderm
Endoderm

Question 6

What are the 3 features of the Primitive Streak during Gastrulation?

Answer 6

• Primitive knot (primitive node)
• Primitive groove
• Primitive pit

Question 7

What germ layer is the Notochord derived from?

Answer 7

Mesoderm

Question 8

What is derived from the paraxial, intermediate, and lateral plate mesoderm?

Answer 8

Paraxial: Somites

• Myotome (muscle)
• Sclerotome (axial skeleton)
• Dermatome (dermis)

Intermediate: Urogenital

• Kidneys
• Gonads

Lateral Plate: Somatic Connective tissue

• Blood
• Lymph
• Mesenteries
• Cardiovascular

Question 9

What stimulates the formation of the neural plate and neural crest cells?

Answer 9

SHH (released from notochord)

Question 10

What 4 structures are derived from neuroectoderm?

Answer 10

• Neural plate
• Neural groove
• Neural folds
• Neural tube

Question 11

What does the neural tube (neuroectoderm) give rise to?

Answer 11

CNS (Brain and Spinal Chord)

- is a rounded hollow tube

Question 12

What germ layer are neural crest cells derived from?

Answer 12

Ectoderm but act like mesoderm

Question 13

What does surface ectoderm give rise to?

Answer 13

skin, hair, nails

Question 14

When do the rostral and caudal neuropores close? (Primary Neurulation)

Answer 14

Rostral neuropore: Day 25
Caudal neuropore: Day 28
(Cervical, Thoracic, and Lumbar regions)

Question 15

When does the caudal eminence form? (Secondary Neurulation)

Answer 15

Days 20-42

Question 16

What tissues are derived from neural crest cells?

Answer 16

• Sensory Nerves
• Spinal ganglia
• Shwann cells
• Enteric Ganglion
• Arachnoid and pia matter
• Melanocytes (pigment in the skin)
• C-cells of the thyroid
• Chromatin cells of the medulla
• Bone and cartilage
• Teeth

Question 17

Major Neurocristopathies arise from issues with what?

Answer 17

Neural Crest cells

Question 18

What types of problems arise from defects in migration and morphogenesis of neural crest cells?

Answer 18

• Cleft lip/palate
• DiGeorge syndrome (thymus)
• Dental abnormalities
• Heart problems
• Eye problems

Question 19

What are the 4 major congenital neural tube defects?

Answer 19

• Spinal bifida occulta (hidden)
• Meningocele (cyst-like sac in meninges) (may or may not have deficits)
• Meningomyelocele (herniation of meninges and spinal chord into a cyst-like sac) (motor and sensory deficits)
• Myelocele (myeloschisis) (Spinal chord cyst and spinal chord is exposed to the environment) (motor and sensory deficits)

(failure of caudal neuropore to close)

Question 20

The 4 major congenital neural tube defects can be prevented with what supplement?

Answer 20

Folate (Vitamin B9)

Question 21

What congenital neural tube defects arise from a failure of the rostral neuropore to close?

Answer 21

• Anencephaly
• Encephalocele (with brain tissue)
• Encephalocele (without brain tissue)

Question 22

Cervical Meningocele and Frontal Encepholocele arise from what failure?

Answer 22

Cervical Meningocele : failure of caudal neuropore to close

Frontal Encephalocele: Failure of the rostral neuropore to close

Question 23

What are the 3 developmental layers of the meninges?

Answer 23

Meninx Primitiva: derived from cells of the sclerotome (neural crest cells migrate and mingle) (mesoderm in origin)

Pachymeninx: dura mater (mesoderm)

Leptomeninges: arachnoid and pia mater (neural crest)

Question 24

What occurs developmentally in week 4?

Answer 24

Folding of the embryo