Early Embryology Flashcards Preview

Step 1 > Early Embryology > Flashcards

Flashcards in Early Embryology Deck (16):
1

What does the embryo enter the uterine cavity as 3 days after fertilization?

Morula

2

What does the morula become by swelling with fluid?

Blastocyst--> formed in the 1st week; called blastocyst when it forms an inner cell mass

3

*What two structures compose the blastocyst?

1. Embryoblast (forms embyro)
2. Trophoblast (forms placenta)

4

What two structures develop from the trophoblast? When?

1. Cytotrophoblast
2. Syncytiotrophoblast
*in the 2nd week

5

What does the cytotrophoblast form?

Primary villi

6

What does the syncytiotrophoblast do?

Implants into the uterine wall and actually produces hCG--> is the outer portion of the trophoblast

7

In the second week, what two layers comprise the embryo?

Epiblast and hypoblast (called bilaminar disk)--> is composed of two germ layers at this point

8

What germ layer does the epiblast give rise to?

ectoderm

9

What structure does mesoderm and endoderm derive from?

primitive streak

10

What two cavities are present in the second week?

1. amniotic cavity
2. yolk sac

11

*Rule of 2's (3 rules)

In the 2nd week:
- 2 germ layers (bilaminar disc; epiblast, hypoblast)
- 2 cavities (amniotic cavity, yolk sac)
- 2 components to placenta (syncytio- and cytotrophoblast)

12

Rule of 3's (1 rule)

3 germ layers in the third week (endoderm, ectoderm, mesoderm)--> process of obtaining the three layers is called gastrulation; cells called gastrula in the 3rd week

13

What week does neural tube form and close?

4th week

14

What weeks does organogenesis take place?

Weeks 3-8; called embryonic period

15

When does implantation occur?

By the 7th day

16

Rule of 4's (2)

By the 4th week:
- 4 heart chambers (heart begins to beat)
-4 limb buds (limbs are growing/present)

Decks in Step 1 Class (63):