Embryonic overview

Question 1

when is the embryonic period

Answer 1

weeks 3-8. most susceptible to teratogens

Question 2

When is embryo organogenesis?

Answer 2

weeks 3-8

Question 3

what is complete and incomplete situs inversus?

Answer 3

1. complete: all organs are mirror images

2. incomplete: only affects single organ

Question 4

What is the primary cause of sirenomelia?

Answer 4

incomplete mesoderm production of the embryo at the caudal region

Question 5

What is a sacrococcygeal teratoma caused from?

Answer 5

failure of primitive streak to disappear at the end of 4 weeks.

Question 6

The notochord is derived from what embryonic cell layer?

Answer 6

mesoderm

Question 7

After neurulation the notochord remains to become what structure in adults?

Answer 7

nucleus pulposus of the intervertebral discs

Question 8

The lateral embryonic folding is required to produce what structures?

Answer 8

the lateral folding helps to form the gut tube. The parietal mesoderm encapsulate quickly which forces some of the yolk sac out and allows the portion that does become captured, to form the gut tube. lined with visceral mesoderm

Question 9

What structure is still intact after the lateral folding takes place? Helps hold the gut tube in place.

Answer 9

dorsal mesentery, which later will assist with holding the abdominal organs “in place”

Question 10

When does lateral folding occur?

Answer 10

week 4.

Question 11

The cephalocaudal folding also takes place during week four, but produces what?

Answer 11

1. places embryo into a fetus, and forms sections such as fore-/mid-/hindgut

Question 12

The surface ectoderm will give rise to what structures?

Answer 12

1. nails, epidermis, hair.

Question 13

The neuroectoderm gives rise to what structure?

Answer 13

ear, eye, nose sensory epithelium

Question 14

The neural tube formation provides what structures?

Answer 14

1. CNS

2. neural crest cells–> PNS

Question 15

What are the mesodermal embryonic derivatives?

Answer 15

1. neuroectoderm
2. paraxial mesoderm
3. intermediate mesoderm
4. lateral plate mesoderm (splanchnic)
5. lateral plate mesoderm (somatic)

Question 16

What does the paraxial mesoderm give rise to?

Answer 16

1. first becomes somites, which then become dermotomes, sclerotomes, and myotomes.
2. give rise to muscle, connective tissue (dermis), and skeleton

Question 17

What does the intermediat mesoderm give rise to?

Answer 17

kidney, ureter, urethra, urinary bladder,

Question 18

What does the lateral plate mesoderm give rise to?

Answer 18

connective tissues and muscles

Question 19

What does the endoderm give rise to?

Answer 19

epithelial lining of the GI and respiratory, and bladder and urethra.

Question 20

What significant things happens during fetal period 9-12?

Answer 20

1. slow head growth
2. ossification
3. RBC production moves from liver to spleen

Question 21

What should be visualized by week 12?

Answer 21

external genitalia

Question 22

What is unique of fetal weeks 13-16?

Answer 22

1. lengthening body
2. hair on scalp
3. eye movement

Question 23

What is unique of weeks 17-20?

Answer 23

1. limb movement
2. vernix caseosa is held in place by lanugo, to protect fetus
3. testes descend

Question 24

What is unique of 21-25 weeks?

Answer 24

weight gain, and surfactant secretion into lungs.

Question 25

What is the earliest that a fetus could be born and potentially survive?

Answer 25

21 weeks, up to this point the lungs have not had time to develop

Question 26

Which develop first finger or toe nails?

Answer 26

finger during week 21-25. toe nails follow at 25-30 weeks

Question 27

When does RBC formation shift from the spleen to bone marrow?

Answer 27

week 28

Question 28

When is pupillary light relfex present in fetus?

Answer 28

30-35 week

Question 29

What method can be used early in pregnancy for determining the fetus status, but has high risk of introducing problems?

Answer 29

chorionic villi sampling

Question 30

Of the two methods to assess fetal status, which one is less threatening to the life of the fetus?

Answer 30

amniocentesis.

*can’t be sampled as early as chorionic villi sampling.