amniotic cavity

Question 1

on what day does amniotic cavity begin to form? how?

Answer 1

day 8. Fluid begins to accumulate between cells of the epiblast. As a result, some epiblast cells are displaced toward the embryonic pole and form the amniotic membrane.

Question 2

what are amnioblasts? amnion?

Answer 2

amnioblasts are the cells that make up the amniotic membrane. the cavity itself is the amnion.

Question 3

how does amniotic membrane grow as amnion grows in volume?

Answer 3

amnioblasts migrate along the cytotrophoblastic roof and contribute to growth of the amniotic membrane. the thin amniotic membrane ultimately consists of a single layer of extraembryonic ectodermal cells lined by nonvascularized extraembryonic mesoderm.

Question 4

what does amniotic membrane look like ultimately?

Answer 4

a single layer of extraembryonic ectodermal cells lined by nonvascularized extraembryonic mesoderm.

Question 5

at what stage is amniotic cavity at week 8?

Answer 5

it emcompasses the embryo and acquires several functions:

1. fluid absorbs shock
2. fluid prevents adherence to the amniotic membrane
3. allows for fetal movement and growth
4. temperature regulation

Question 6

how does growth of the amnion influence the yolk sac?

Answer 6

the growth pushes the yolk sac and connecting stalk together

Question 7

what is the vitelline duct?

Answer 7

yolk sac

Question 8

what do vitelline duct and yolk sac become incorporated into?

Answer 8

the umbilical cord

Question 9

what happens to the yolk sac and vitelline duct by birth?

Answer 9

they disappear. the amniotic membrane eventually grows to cover the umbilical cord.