Development of extra embryonic membranesII

Question 1

WHat does the yolk sac do for the embryo other than provide nutrients?

Answer 1

Acts as a preliminary circulatory system

Question 2

How does the yolk sac act as a primitive circulatory system?

Answer 2

Delivers nutrients via a primitive aorta

Question 3

What is vitelline circulation?

Answer 3

the blood flow system connecting an embryo to its yolk sac

Question 4

What do the visceral endoderm cells of the yolk sac do?

Answer 4

Synthesise serum proteins

Question 5

Why does vitelline circulation occur?

Answer 5

At that stage there is not yet a heart

Question 6

What is extraembryonic hematopoiesis?

Answer 6

Primary erythroid cells emerging from the yolk sac blood islands

Question 7

Which pronuclei is responsible for a lot of the extraembryonic material

Answer 7

Paternal pronuclei

Question 8

What kind of structure is the allantois?

Answer 8

Extra embryonic membrane

Question 9

Where does the allantois originate?

Answer 9

Endoderm

Question 10

What is the allantois an extension of?

Answer 10

Early hindgut

Question 11

Which end of the developing bladder is the allantois connected to?

Answer 11

The superior end

Question 12

Role of allantois in birds and reptiles?

Answer 12

Reservoir for wastes

Question 13

Role of allantois in mammals?

Answer 13

Associated and eventually incorporated with the connecting stalk which becomes the umbilical cord

Question 14

What do the blood vessels of the allantois develop into?

Answer 14

Blood vessels of the umbilical cord

Question 15

What is the urachus?

Answer 15

A structure that removes nitrogenous waste from the fetal bladder in the fist trimester

Question 16

What ends up happening to the urachus?

Answer 16

Seals off and obliterates around the 12th week of gestation

Question 17

What is left of the urachus?

Answer 17

Umbilical ligament

Question 18

What is the umbilical ligament?

Answer 18

A small fibrous cord between the bladder and umbilicus left over from the remains o of the urachus

Question 19

What does the body stalk become?

Answer 19

Umbilical cord

Question 20

What are the two separate vessels formed inside the umbilical cord?

Answer 20

Vitelline duct and the allantois

Question 21

What is the amniotic cavity?

Answer 21

a closed sac that contains amniotic fluid

Question 22

Where is the amniotic cavity found?

Answer 22

Between the embryo and the amnion

Question 23

What is contained within the amniotic fluid?

Answer 23

Nutrients 4 the embryo, skins from the embryo, stem cell source

Question 24

What happens to the amniotic cavity over time?

Answer 24

Gets bigger

Question 25

Trend of sizes over time for the embryo, yolk sac and amniotic cavity?

Answer 25

embryo--> gets bigger Yolk sac-->gets smaller Amniotic cavity-->gets bigger

Question 26

What is the amniotic cavity initially lined with?

Answer 26

Ectoderm

Question 27

What is the amniotic cavity covered with?

Answer 27

Extra embryonic mesoderm

Question 28

WHat happens to the amniotic sac as a result of folding of the embryonic disc?

Answer 28

The amniotic membrane is drawn ventrally over the embryo, enclosing the embryo within the amniotic sac

Question 29

What is the amniotic fluid?

Answer 29

Circulated by foetal inhaling and swallowing. Replaced by foetal exhalation and urination.

Question 30

What is a small amount of amniotic fluid an indication of?

Answer 30

Poor kidney development/poor embryonic development