Embryology II

Question 1

When are the neuropores expected to fuse together?

Answer 1

At the fourth week of gestation (p.409)

Question 2

What occurs if the neuropores do not fuse together at the fourth week of gestation?

Answer 2

Neural tube defects (p.409)

Question 3

What is a neural tube defect?

Answer 3

A persistent connection between the amniotic cavity and spinal canal (p.409)

Question 4

What amniotic fluid and maternal serum protein is elevated in the instance of a neural tube defect?

Answer 4

Elevated a-fetoprotein (AFP) (p.409)

Question 5

What amniotic protein is used to confirm a neural tube defect in a fetus?

Answer 5

Elevated acetylcholinesterase (p.409)

Question 6

What is spina bifida occulta?

Answer 6

Failure of the spinal canal to close without structural herniation; dura is intact (p.409)

Question 7

Where is spina bifida occulta usually seen?

Answer 7

At the lower vertebral levels (p.409)

Question 8

What physical findings are associated with spina bifida occulta?

Answer 8

A tuft of hair or skin dimple at the level of the bony defect (p.409)

Question 9

What is a meningocele?

Answer 9

When the meninges (but not the spinal cord) herniate through the spinal canal defect (p.409)

Question 10

What is a meningomyelocele?

Answer 10

When the meninges and spinal cord herniate through the spinal canal defect (p.409)

Question 11

Name three neural tube defects.

Answer 11

Spina bifida occulta, meningocele, meningomyelocele (p.409)

Question 12

Name two forebrain embryologic anomalies.

Answer 12

Anencephaly, holoprosencephaly (p.409)

Question 13

What is anencephaly?

Answer 13

Malformation of the anterior neural tube resulting in no forevrain and open calvarium (p.409)

Question 14

What are the clinical findings associated with anencephaly?

Answer 14

Increased a-fetoprotein, polyhydraminos (no swallowing centre in the brain) (p.409)

Question 15

What maternal condition is associated with anencephaly?

Answer 15

DM type I (p.409)

Question 16

What can decrease maternal risk of a fetus with anencephaly?

Answer 16

Folate supplementation (p.409)

Question 17

What is holoprosencephaly?

Answer 17

Failure of left and right hemispheres to separate (p.409)

Question 18

When does holoprosencephaly occur in a fetus?

Answer 18

During weeks 5-6 (p.409)

Question 19

What is the etiology of holoprosencephaly?

Answer 19

Multifactorial; may be related to mutations in sonic hedgehog signaling pathway (p.409)

Question 20

Name a common clinical finding associated with mild holoprosencephaly.

Answer 20

Cleft lip/palate (p.409)

Question 21

Name a common clinical finding associated with severe holoprosencephaly.

Answer 21

Cyclopia (p.409)

Question 22

Name two posterior fossa malformations.

Answer 22

Chiari II (Arnold Chiari malformation); Dandy-Walker malformation (p.409)