W2 Organ Formation

Question 1

What period of fetal development is the most sensitive to teratogens and why?

Answer 1

4-8th week; when main organs are established

Question 2

What marks the start of neurulation?

Answer 2

Thickening of cells (neural plate)

Question 3

Neural plate becomes __ and __.

Answer 3

neural tube, neural crest

Question 4

What is derived from the neural tube? Neural crest?

Answer 4

Neural tube: CNS

Neural crest: PNS

Question 5

Pharyngeal arches move from side to middle of embryo to form our __ and __.

Answer 5

Face, neck

Question 6

What day does anterior neuropore close? Posterior neuropore?

Answer 6

Anterior: Day 25
Posterior: Day 27

Question 7

What are the four ventricles of the brain? This is the CNS.

Answer 7

2 Forebrain (I, II)
Midbrain (III)
Hindbrain (IV)

Question 8

Telencephalon (forebrain) gives rise to ___ tissues.
Diencephalon (forebrain) gives rise to ___ tissues.
Mesencephalon (midbrain) gives rise to ___ tissues.

Answer 8

Olfactory
optic
oculomotor

Question 9

What causes anencephaly (no brain)? What day of fetal development can it be observed?

Answer 9

Neural closure issue at anterior neuropore; observed after 25 days

Question 10

What causes spina bifida? What day can of fetal development can it be observed?

Answer 10

Neural closure issue at posterior neuropore; observed after 27 days

Question 11

Anencephaly and spina bifida are results of issues with __.

Answer 11

neuropore closure (neural tube defect)

Question 12

What is AFP? Alfa feto protein

Answer 12

Protein produced by liver of the fetus

Question 13

How do you test for neural tube defect?

Answer 13

Maternal blood test for detection of AFP (alpha feto protein); non-invasive

Question 14

Mesoderm organization:
axial
paraxial
intermediate
lateral plate

Answer 14

axial (neural tube)
paraxial (somites)
intermediate (kidney)
lateral plate (parietal and visceral pleura)

Question 15

What are the three tissues that the somites give rise to? (mesoderm)

Answer 15

Sclerotome (all bones except face and clavicle)

Myotome (all voluntary muscles except few oculomotor muscles)

Dermatome (all dermis)

Question 16

What is the main function of the notochord?

Answer 16

Induce surrounding cells to differentiate; organizing center

Question 17

___ and ___ retain memory after they migrate. The nerves that innervate them find the corresponding sections in the spinal cord.

Answer 17

Dermatome, myotomes

Question 18

Dorsal area of neural crest become?

Answer 18

Melanocytes

Question 19

Neural crest migrate into pharyngeal arches and form most of the __, __, and __ region.

Answer 19

Skull, face, neck

Question 20

Pharyngeal arch 1 gives rise to maxillary and mandibular tissues particularly sensitive to __ __, which may give rise to cleft palate or micrognathia (small jaw)

Answer 20

retinoic acid (teratogenesis)

Question 21

What is Hirschsprung’s Disease? How does it lead to megacolon?

Answer 21

Also called congenital or aganglionic megacolon.

Cells of neural crest don’t make it all the way to colon (abnormal neural crest cell migration); absence of enteric ganglion cells

Sustained contraction of the aganglionic segment causes obstruction and distension, leading to megacolon

Question 22

What is Piebald pigmentation? What other conditions does the baby have?

Answer 22

mutation of c-kit receptor required for neural crest cell migration

kit receptor is also needed for blood stem cell and germ development

Baby with Piebald pigmentation is also anemic and sterile.