Lesson 3A (Part 2)

Question 1

What does the decidua capsularis do?

Answer 1

It covers the blastocyst and separates it from the endometrial cavity

Question 2

What is the decidua parietalis/vera?

Answer 2

The remainder of the endometrium not directly in contact with the blastocyst

Question 3

How long can implantation take?

Answer 3

4 days

Question 4

What does the inner mass cell develop into during the time of implantation? (2)

Answer 4

1. Bilaminar embryonic disc

2. Amniotic cavity

Question 5

What are the 2 layers of the bilaminar embryonic disc?

Answer 5

1. Epiblast

2. Hypoblast

Question 6

What forms from the chorion?

Answer 6

The placenta

Question 7

Which way does the hypoblast layer face?

Answer 7

Faces the blastocele

Question 8

What does the blastocele become?

Answer 8

The primitive yolk

Question 9

Which way does the epiblast layer face?

Answer 9

The amniotic cavity

Question 10

What does the amniotic cavity eventually surround?

Answer 10

The embryo

Question 11

What is visible within the gestational sac on US?

Answer 11

The amniotic membrane

- little circle halo

Question 12

What does the amniotic membrane eventually fuse with?

Answer 12

The chorionic walls of the gestational sac

Question 13

What does the blastocele become?

Answer 13

The primitive yolk sac

Question 14

How do you get the secondary yolk sac?

Answer 14

The pitching off of the primitive yolk sac

- can see this on US

Question 15

What does the yolk sac produce?

Answer 15

The embryo’s first blood cells

Question 16

What is the entire bilaminar disk surrounded by?

Answer 16

Trophoblastic cells

Question 17

What do the trophoblastic cells form?

Answer 17

The chorion

Question 18

What is the space within the chorion called?

Answer 18

The chorionic cavity

- this will be your visible gestational sac

Question 19

What does the chorion project as it develops?

Answer 19

Villi

- into the surrounding decidua, completely surrounding the blastocyst

Question 20

What 2 zones will the chorion differentiate into?

Answer 20

1. Chorion leave
   - smooth
2. Chorion frondosum
   - villous

Question 21

What does the villi do on one side of the decidua capsularis?

Answer 21

It will degenerate

- this leaves the smooth chorion (chorion leave)

Question 22

What does the villi do on the side of the decidua basalis?

Answer 22

It will proliferate

- this is the villous chorion (chorion frondosum)

Question 23

What will the chorion frondosum become?

Answer 23

The embryonic portion of the placenta

Question 24

What does the embryonic portion of the placenta develop?

Answer 24

Large intervillous spaces

- where maternal blood will be flooded to provide nutrients

Question 25

What does the fetal portion of the placenta eventually occupy?

Answer 25

Almost all of the decidua basalis, leaving only the basal layer intact

Question 26

What does the chorion frondosum and the decidua basalis form?

Answer 26

The fetal and the maternal components of the placenta

- respectively

Question 27

What does the hCG placenta begins to secrete as the CL starts to degenerate? (2)

Answer 27

1. Estrogen

2. Progesterone

Question 28

What happens during utero-placenta circulation (maternal aspect)? (2)

Answer 28

1. The intervillous spaces will receive oxygenated blood from the endometrial (decidual) spiral arteries
2. The intervillous spaces are drained by the endometrial veins, branches of the uterine veins