Exam 1 Embryonic and Fetal Periods

Question 1

What day does the neural plate begin to fold inward?

Answer 1

Day 22

Question 2

What day does the cranial neuropore close?

Answer 2

Day 24-25

Question 3

What day does the caudal neuropore close?

Answer 3

Day 26-27

Question 4

What are the only derivatives of the neural crest that we need to know?

Answer 4

Parasympathetic ganglia of CN III, VII, IX, and X
Sensory ganglia of CN V, VII, VIII, IX, and X
Autonomic and dorsal root ganglia

Question 5

What will surface ectoderm give rise to?

Answer 5

1) Epidermis, hair, nails cutaneous, and mammary glands
2) anterior pituitary gland
3) enamel of teeth
4) internal ear
5) lens of the eye

Question 6

What structures are derived from the paraxial mesoderm?

Answer 6

• axial skeleton, voluntary musculature, and part of the dermis

Question 7

What structures are derived from the intermediate mesoderm?

Answer 7

• urinary system and parts of the genital system

Question 8

What structures are derived from the lateral plate mesoderm?

Answer 8

• It will split into 2 layers:
  
  • ->splanchnic mesoderm: endoderm (visceral and associated with organs ( airway, esophagus, smooth muscle, etc.)
  • ->somatopleuric mesoderm: extoderm

Question 9

What day does the first somite become somitomeres?

Answer 9

Day 20 the 8th somitomere becomes a somite.

Question 10

What are the total number of somites that are left?

Answer 10

• 37 pairs

Question 11

What does the lateral folding of the embryo result in?

Answer 11

Incorporation of the allantois which eventually forms the cloaca.

Question 12

What bounds the primitive gut tube at each end by?

Answer 12

bound by the buccopharyngeal and cloacal.

Question 13

What does the endoderm form besides allantois, endoderm, and GI tract?

Answer 13

• epithelium of the respiratory tract, bladder, urethra tympanic cavity, and auditory tube
• parenchyma of the thyroid, parathyroid, liver, and pancreas
• Stroma of the tonsils and thymus

Question 14

What structures are susceptible to teratogens during the fetal period?

Answer 14

• Brain, eyes, external genitalia, teeth, ears, palate

Question 15

What are the significant embryological milestones for weeks 9-12?

Answer 15

• Week 9 - the liver is a major site of erythropoeisis.

- After week 9 the external genitals can be distinguished as male or female.

Question 16

What are the significant embryological milestones for weeks 13-16?

Answer 16

• Sites of ossification are evident (cartilage–> bone)

- Eye movements and the eyes are facing forward.

Question 17

What are the significant embryological milestones for weeks 17-20?

Answer 17

• Primary ovarian follicles are formed

- Testes are descending

Question 18

What are the significant embryological milestones for weeks 21-25?

Answer 18

• surfactant is beginning to be secreted in the lungs.

Question 19

What are the significant embryological milestones for weeks 26-29?

Answer 19

• Lungs are now capable of breathing
• The CNS is capable of controlling breathing and body temperature
• Spleen is still making blood cells; by 28 weeks blood formation shifts to the bone marrow

Question 20

What are the significant embryological milestones for weeks 35-38?

Answer 20

Referred to as a “finishing period” this involves the final preparations of tissues important in the transition to the outside world (cardio and respiratory)

Question 21

What is the blood producing organs in the first 12 weeks?

Answer 21

yolk sac

Question 22

What is the major blood producing organs during week 12-30?

Answer 22

• week 12-30 the liver

- week 12-24 the spleen

Question 23

What is the major blood producing organs during week 30?

Answer 23

• Bone marrow

Question 24

What are the reasons an amniocentesis would be performed?

Answer 24

• mother’s advanced age
• mother of child with previous Down’s child
• Parents carry chromosomal abnormalities
• Parents are x-linked carriers
• Hx neural tube defects
• Parents have inborn errors of metabolisms