Implantation to Gastrulation

Question 1

What does the syncytiotrophoblast do?

Answer 1

digests the uterine lining to allow implantation, can cause implantation bleeding/spotting.

Question 2

The epiblast is the precursor to_____

Answer 2

other body cells

Question 3

In week 2 what 2 layers form in the embryo, and what 2 layers form in the trophoblast?

Answer 3

Embryo- epiblast and hypoblast

Trophoblast - syncytiotrophoblast and cytotrophoblast

Question 4

What are the two cavities formed in week 2?

Answer 4

Amniotic sac cavity and yolk sac cavity

Question 5

What is the purpose of the amniotic membrane/fluid?

Answer 5

prevents dessication of embryo AKA drying out

Question 6

What does hCG signal tell the ovary to do?

Answer 6

Continue to secrete the necessary hormones to maintain the pregnancy and prevent menses.

Question 7

The critical period of development occurs in which weeks?

Answer 7

3-8

Question 8

Where is the XE found (extraembryonic Mesoderm)?

Answer 8

between the inner lining of cytotrophoblast and yolk sac

Question 9

Is the mesoderm intraembryonic or extramembryonic?

Answer 9

extraembryonic

Question 10

What do the trophoblastic lacunae do?

Answer 10

allows maternal vessels a place to supply blood to the embryo.

Question 11

What does the connecting stalk become?

Answer 11

the umbilical cord

Question 12

By week 3 there are 3 layers of trophoblast and 3 cavities, what are they?

Answer 12

syncytiotrophoblast, cytotrophoblast, XE mesoderm

Amnion, yolk sac, chorion

Question 13

Somatic =

Answer 13

wall of the body cavity

Question 14

Splanchnic =

Answer 14

visceral “internal organs”

Question 15

What is significant about the chorionic villus?

Answer 15

a sample of it can be used to test for genetic diseases/birth defects

Question 16

Prior to gastrulation there embryo exists as a bilaminar disk, gastrulation changes this to trilaminar, what are the 3 germ layers?

Answer 16

Endoderm, Mesoderm, Ectoderm

Question 17

What happens to cells at the primitive streak?

Answer 17

differentiation

Question 18

The primitive streak is the future ____ of the embryo

Answer 18

axis

Question 19

Elongation of the primitive streak occurs through the addition of ____ cells to the _____ end

Answer 19

epiblast cells to the caudal end

Question 20

Mesenchyme can be thought of a primitive form of _____

Answer 20

connective tissue

Question 21

Sacrococcygeal Teratoma is thought to occur as a result of

Answer 21

multipotent cells from the anterior portion of the primitive streak

Question 22

Germ layer defects result in VATERL

Answer 22

Vertebral abnormalities, Anal atresia, Tracheoesophageal fistula, Renal defects & Limb defects

Question 23

What is a cause of germ layer defects?

Answer 23

abnormal gastrulation AKA the migration of the mesoderm is disturbed

Question 24

Major week 3 events include

Answer 24

Appearance of the primitive streak
Differentiation of the 3 primary germ layers
Development of the notochord

Question 25

The notochord is eventually replaced by the

Answer 25

vertebral column

Question 26

Notochord functions

Answer 26

Structure - rigid axis around which embryo develops
Skeletal - Foundation which the vertebral column forms
Induction- leads to formation of the neural tube AKA nervous system