Exam 4: Embryogenesis II

Question 1

What types of changes does the blastocyst undergo

Answer 1

morphological and function

Question 2

Why does the blastocyst undergo changes

Answer 2

Prepare for uterine life and organogenesis

Question 3

What three changes does the blastocyst undergo

Answer 3

Hatching
Elongation
Migration

Question 4

What two structures make up the blastocyst

Answer 4

Trophectoderm and ICM

Question 5

What structures does the ICM give rise to

Answer 5

Ectoderm, mesoderm, endoderm

Question 6

What structure establishes first contact with the uterus

Answer 6

Trophectoderm

Question 7

What does the trophectoderm differentiate into

Answer 7

Polar trophectoderm: on top of ICM mass
Parietal trophectoderm: around the blastocoele

Question 8

What does the ICM differentiate into

Answer 8

Primitive endoderm: on the blastocoele side, visceral (yolk sac) and parietal
Primitive ectoderm: forms most of the tissues

Question 9

What does the endoderm form

Answer 9

Intestines, liver, lungs

Question 10

What does the mesoderm form

Answer 10

Kidney, testis, skin, muscle

Question 11

What does the ectoderm form

Answer 11

Nervous system and skin

Question 12

What are the extra embryonic membranes

Answer 12

Yolk sac, chorion, allantois, ammnion

Question 13

What derives the yolk sac, what covers it

Answer 13

Primitive endoderm
Mesoderm

Question 14

What derives the chorion, what lines it

Answer 14

Trophectoderm
Mesoderm

Question 15

What derives the allantois, what lines it

Answer 15

Primitive gut (endoderm)
Mesoderm

Question 16

What forms the allantochorion

Answer 16

Fusion of allantois and chorion

Question 17

What derives the amnion in rodents and primates

Answer 17

Primitive ectoderm

Question 18

What derives the amnion in ruminants

Answer 18

The amniotic folds which derive from the trophectoderm and mesoderm

Question 19

4 functions of the chorion

Answer 19

1. Enables fetus to get oxygen and nourishment
2. Secretes hormones that cause mother’s uterus to retain fetus
3. Produces regulators of the immune response so mother will no reject embryo
4. Form embryonic layer of placenta

Question 20

4 functions of the amnion

Answer 20

1. Allows symmetrical external growth of embryo
2. Cushions embryo against jolts
3. Control embryo’s body temperature
4. Enables fetus to move freely, aids muscular and skeletal development

Question 21

3 functions of the yolk sac

Answer 21

1. Transfer of nutrients during first weeks
2. Initial blood development
3. Store primordial germ cells during third week before they migrate to developing gonads

Question 22

2 functions of the allantois

Answer 22

1. Collects liquid waste
2. form the allanto-chorion

Question 23

Maternal portion of the placenta

Answer 23

Uterine endometrium

Question 24

Fetal component of the placenta

Answer 24

Chorion