ch.3 embryology week 2

Question 1

week 2: two layered-embryo
-what happens to the embryoblast as implantation occurs?

Answer 1

-early differentiation of the inner cell mas begins

Question 2

week 2: two layered-embryo
-by day 9, what are the two flat sheets of cells the inner cell mass divides into?

Answer 2

-epiblast: over, upon; in the direction of the uterine wall. amniotic sac extends from it.
-hypoblast: under, beneath. yolk sac extends from it

Question 3

week 2: two layered-embryo
-bilaminar embryonic disc

Answer 3

-made by the epiblast and hypoblast
-precursor for the entire body

Question 4

week 2: amniotic sac and yolk sac
-describe the amniotic sac and the yolk sac

Answer 4

-amniotic sac: extension of the epiblast; the amniotic fluid acts as a buffer to protect the developing embryo from physical shock until birth.
-yolk sac: extension of the hypoblast; contains an insignificant amount of yolk, however it gives rise to parts of the inner digestive tube and the earliest blood supply.

Question 5

week 2: completion of implantation
-what hormone is produced at the end of the implantation?

Answer 5

• a layer of the trophoblast begins to produce hCG hormone, the basis for all pregnancy tests.