2: Embryology

Question 1

When is the pre-embryonic period?

Answer 1

Weeks 1-2

Question 2

When is the embryonic period?

Answer 2

Weeks 3-8

Question 3

When is the fetal period?

Answer 3

Weeks 9-38

Question 4

What is an oocyte?

Answer 4

female sex cell; also known as an egg

Question 5

What happens at fertilization?

Answer 5

occurs as the pronucleus (nucleus) of the sperm fuses with the pronucleus (nucleus) of the oocyte

Question 6

What is a zygote?

Answer 6

fertilized egg; single cell

Question 7

What is a conceptus?

Answer 7

zygote and its associated membranes

Question 8

What happens during cleavage?

Answer 8

The conceptus splits until it turns into a morula, but its size remains the same

Question 9

What is a morula?

Answer 9

The 16-cell product of cleavage from a conceptus

Question 10

What are the 3 parts of a blastocyst?

Answer 10

Inner Cell Mass
Trophoblast
Blastocoel (Fluid-filled area)

Question 11

What is blastocoel?

Answer 11

The fluid in a blastocyst

Question 12

What are the two products of a trophoblast as the blastocyst burrows into the uterine wall?

Answer 12

Cytotrophoblast
Syncytiotrophoblast

Question 13

What are the functions of the trophoblast?

Answer 13

1. Burrows into the uterine lining during implantation
2. Builds the chorion that surrounds the embryo and fetus
3. Helps to form the placenta

Question 14

What is the structure and function of syncytiotrophoblast?

Answer 14

Implantation!

a multinucleated body that digests endometrial cells to firmly secure the blastocyst to the uterine wall

Question 15

How many days until implantation starts after conception? How many until it finishes?

Answer 15

Starts at 6-7, finishes around 9

Question 16

What becomes of the inner cell mass of a blastocyst? (What parts)

Answer 16

Bilaminar disc
1. Epiblast
2. Hypoblast

Question 17

What is the function of the hypoblast?

Answer 17

Gives off cells that helps form the yolk sac

Question 18

What is the function of a yolk sac while attached to the epiblast?

Answer 18

Helps make blood

Question 19

What is the function of the amnion?

Answer 19

Later forms the amniotic sac

Question 20

During what period does the primitive streak form?

Answer 20

Embryonic Period

Question 21

In what layer does the primitive streak form?

Answer 21

Epiblast

Question 22

In what end of the epiblast does the primitive streak begin?

Answer 22

Starts in caudal end, forms toward cephalic end

Question 23

What is the end product of gastrulation? What is it called?

Answer 23

Cells from the epiblast fill into the primitive streak resulting in the primary germ layer
1. Ectoderm
2. Mesoderm
3. Endoderm

Question 24

From which primary germ layer forms the skin and nervous system?

Answer 24

Ectoderm

Question 25

From what primary germ layer forms the muscular system, skeletal system, heart, and kidneys?

Answer 25

Mesoderm

Question 26

From what primary germ layer forms the respiratory system and digestive system?

Answer 26

Endoderm

Question 27

What two types of folding follow gastrulation?

Answer 27

Transverse and cephalocaudal folding

Question 28

What is the product of neurulation? What becomes of it?

Answer 28

Neural tube becomes the brain and spinal cord

Question 29

What process follows neurulation?

Answer 29

Organogenesis

Question 30

During what period does the primary germ layer form?

Answer 30

Embryonic

Question 31

During what period do transverse and cephalocaudal folding occur?

Answer 31

Embryonic

Question 32

During what period does gastrulation occur?

Answer 32

Embryonic

Question 33

During what period does organogenesis occur?

Answer 33

Embryonic

Question 34

By what week does a rudimentary organ system develop?

Answer 34

Week 8