H/E Lecture 2

Question 0

What is the name of the cells formed during cleavage and mitotic divisions?

Answer 0

Blastomeres

Question 1

What are the five events that take place in week 1?

Answer 1

Cleavage
Compaction
Cavitation
Hatching
Implantation

Question 2

What is mosaicism?

Answer 2

Non disjunction during cleavage.

Question 3

What is formed after compaction after the 8 cell stage?

Answer 3

The morula

Question 4

What are the two types of cells in the morula?

Answer 4

Inner and outer cell mass

Question 5

What is cavitation and what is the new structure created?

Answer 5

Uterine fluid pumped into the morula forms a cavity transforming the morula into the blastocyst.

Question 6

The inner cell mass becomes the blank? That gives rise to the blank?

Answer 6

Embryoblast gives rise to the embryo

Question 7

The outer cell mass becomes the blank that gives rise to the blank?

Answer 7

Trophoblast

Fetal placenta

Question 8

What is hatching?

Answer 8

The blastocyst hatches from the zona pellucida.

Question 9

What are some functions of the zona pellucida?

Answer 9

Prevents polyspermy

Prevents premature implantation

Question 10

Which pole of the blastocyst implants?

Answer 10

Embryonic pole does

The other pole is the abembryonic pole

Question 11

When is this called a zygote?

Answer 11

After fertilization when a diploid cell is formed from two haploid cells.

Question 12

What events happen in week two?

Answer 12

Implantation completed (uteroplacental circulation is established)
Bilaminar disc formed (Embryoblast differentiates into two-layered disc)

Question 13

What does the trophoblast become during week two?

Answer 13

Cytotrophoblast

Syncytiotrophoblast

Question 14

What does the Embryoblast become during week two?

Answer 14

Epiblast

Hypoblast

Question 15

Of trophoblast and Embryoblast, which give rise to the fetus, amnion, and chorion?

Answer 15

Trophoblast becomes part of chorion

Embryoblast becomes fetus, amnion, and part of chorion

Question 16

What is vascular lacunae?

Answer 16

Pools of maternal blood near fetal placenta

Question 17

What is the cytotrophoblast?

Answer 17

Mitotic cells that give rise to the syncytiotrophoblast.

Question 18

What is the syncytiotrophoblast?

Answer 18

Forms syncytium that erodes endometrium and it’s vessels.

Question 19

What is hCG?

Answer 19

Human chorionic gonadotropin
Secreted by syncytiotrophoblast 
Maintains progesterone secretion in ovaries to promote uterine blood flow to nourish fetus.
Used for pregnancy test after day 8
Morning sickness link

Question 20

Name two complications from mislocated implantation.

Answer 20

Ectopic pregnancy is implantation outside the body of the uterus.
Placenta previa is implantation near the cervical opening.

Question 21

What is a molar pregnancy?

Answer 21

Trophoblast implants, but Embryoblast is incomplete or absent. May produce benign tumor called hydatidiform mole

Elevated hCG secretion

Question 22

What is choriocarcinoma?

Answer 22

Malignant tumor of trophoblast.

Elevated hCG

Question 23

What is the bilaminar disc?

Answer 23

The Embryoblast becomes two layers:
Hypoblast
Epiblast

Question 24

What is the hypoblast and where does it come from?

Answer 24

Comes from the bilaminar disc from the Embryoblast. It divides and migrates to line the blastocyst cavity. This becomes the primary yolk sac.

Question 25

What does the epiblast do and where does it come from?

Answer 25

One layer of the bilaminar disc that comes from the Embryoblast. It undergoes cavitation to form the amniotic cavity.

Question 26

How does the chorionic cavity form?

Answer 26

The EM or extraembryonic mesoderm forms next to the hypoblast. Then spaces appear in this layer that grow and push the primary yolk sac in around the bilaminar disc to form the secondary yolk sac and the chorionic cavity.

Question 27

What three layers make up the chorion?

Answer 27

Cytotrophoblast Syncytiotrophoblast Extraembryonic mesoderm

Question 28

What is the general time frame for events in first two weeks?

Answer 28

``` Day 1 zygote is formed in ampulla Day 4 morula enters uterus Day 6 implantation of blastocyst begins Day 8 positive pregnancy test End of week two implantation complete and bilaminar disc is formed ```