Weeks 9-40

Question 1

What happens in weeks 9-40?

Answer 1

Growth of fetus

Question 2

What does endovascular invasion into uterine wall by trophoblast result in?

Answer 2

Epithelial to endothelial transformation
Growth of larger vessels
Hybrid vessels w/ cells from both embryo and mother

Question 3

What two membranes fuse to form placenta?

Answer 3

Decidua basilis (uterus) and chorion frondosum

Question 4

What two membranes fuse to form fetal membrane?

Answer 4

Chorionic and amniotic membranes

Question 5

What is the function of the placenta?

Answer 5

Exchange of gases (O2 and CO2)
Exchange of nutrients and electrolytes
Transmission of maternal antibodies (IgG)
Hormone production
Amnio-ectodermal junction - “umbilical ring” - consisting of connecting stalk, yolk stalk, chorionic cavity connection

Question 6

What hormones does placenta release?

Answer 6

Progesterone, Estriol, hCG, somatomamotropic

Question 7

What structure produces progesterone until the placenta forms?

Answer 7

corpus luteum

Question 8

What is the function of somatomamotropin?

Answer 8

Tells the mother’s body to give nutrients preferentially

to the fetus and also starts changes in breast tissue

Question 9

What is function of hCG?

Answer 9

Maintain corpus luteum

Question 10

What type of twins arise from two oocytes?

Answer 10

dizygotic (fraternal) – have separate fetal membranes

Question 11

What type of twins arise from one oocyte?

Answer 11

monozygotic (identical)

Question 12

Q: What type of twins may have one or two amniotic cavities?

Answer 12

A: monozygotic

Question 13

Q: What type of twins always have a common chorionic cavity?

Answer 13

A: monozygotic

Question 14

What type of twins have two separate chorionic cavities?

Answer 14

Dizygotic

Question 15

What is the space called that develops between the splanchnopleuric and somatopleuric extraembryonic mesoderm?

Answer 15

A: chorionic cavity

Question 16

Q: What layer is the source of all three germ layers?

Answer 16

A: epiblast

Question 17

Q: The appearance of the notorchord causes what?

Answer 17

Thickening of the ectoderm (neural plate). The induction of the neuroectoderm is called neurulation.

Question 18

Q: Bones and cartilage of the face arise from what?

Answer 18

A: neural crest

Question 19

Q: The dorsomedial portion of the paraxial mesoderm will become what? Dorsolateral portion?

Answer 19

Epaxial (back) muscles

The dorsolateral portion migrates to become the precursor oflimb and body wall musculature

Question 20

What is the somatic/parietal mesoderm contiguous with?

Answer 20

the extraembryonic mesoderm covering the amnion

Question 21

Q: What is the splanchnic/visceral mesoderm contiguous with?

Answer 21

the extraembryonic mesoderm covering the yolk sac

Question 22

What layer of the lateral plate mesoderm will cover the organs and form the wall of the gut?

Answer 22

Visceral/splanchnic layer along with underlying endoderm will form the wall of the gut

Question 23

Q: What layer of the lateral plate mesoderm will line the intraembryonic cavity?

Answer 23

the parietal/somatic layer along with the overlaying ectoderm will line the intraembryonic cavity