Intro to Embryology

Question 1

How many cells are present in the morula stage and what are they called?

Answer 1

16-32 Blastomeres

Question 2

A ball of cells with a fluid filled cavity.

Answer 2

Blastocyst

Question 3

Embryoblast

Answer 3

The inner cell mass of the blastocyst stage.

Question 4

The outer cell mass of the Blastocyst

Answer 4

Trophoblast

Question 5

What is the job of the trophoblast?

Answer 5

To contribute to support tissue, placenta

Question 6

What happens during the blastocyst stage?

Answer 6

The zona pellucida begins to disintegrate. The blastocyst implants into the uterus between Days 6 and 7

Question 7

What occurs during week 2 of fertilization?

Answer 7

The blastocyst flattens into a two-layered bilaminar disc which is squeezed between two fluid filled cavities, the amniotic above and yolk sac below.

Question 8

Cyntotrophoblast

Answer 8

Mitotic inner layer of cells of the trophoblast

Question 9

Multi-nucleated mass of fused cells in the Trophoblast. This layer secretes the hormone HCG

Answer 9

Synctiotrophoblast

Question 10

What two outer layers are established during fertilization?

Answer 10

Zona pellucida and the Corona Radiata

Question 11

Describe the structure of the placenta.

Answer 11

Two layers. The maternal, endometrial lining of the uterus. And the fetal, cytotrophoblast and synctiotrophoblast form the chorion and chorionic cavity of the placenta.

Question 12

Formation of a three layered embryo consisting of three germ layers.

Answer 12

Gastrulation

Question 13

What are the three primary germ layers and what do they give rise to?

Answer 13

Ectoderm, Mesoderm, and Endoderm

Question 14

Neural Tube

Answer 14

A hollow tube that gives rise to most of the CNS. End of the tube closes at days 26 and 28.

Question 15

Ectoderm cells that fail to be incorporated into the tube, which form a crest around the tube.

Answer 15

Neural Crest

Question 16

When does the Neural Tube begin to form?

Answer 16

Days 19 to 23.

Question 17

The cloaca is also known as what?

Answer 17

The future anus

Question 18

The connecting stalk is known as what?

Answer 18

Future umbilicus

Question 19

What forms from the ectoderm?

Answer 19

The epidermis and the NS (neural tube and crest)

Question 20

Forms the primitive connective tissue and mesenchyme between the endoderm and ectoderm.

Answer 20

Mesoderm

Question 21

The endoderm becomes…

Answer 21

The trachea, bronchi, lungs, liver, gall bladder, and pancreas

Question 22

Mesoderm differentiates into…

Answer 22

Support tissues (connective tissue, cartilage), muscle, blood, and blood vessels. Also forms the urogenital system.

Question 23

Coelem

Answer 23

Body cavities, or spaces in the mesoderm

Question 24

Which system is the first to function?

Answer 24

The cardiovascular system.

Question 25

When does the heart begin to beat?

Answer 25

Week 4

Question 26

Blocks of mesoderm which form along the sides of the neural tube.

Answer 26

Somites

Question 27

How many somites typically form in the embryo?

Answer 27

42 to 44

Question 28

Somites give rise to...

Answer 28

1. Myotome 2. Sclerotome 3. Dermatome

Question 29

Skeletal muscles of the back and body wall

Answer 29

Myotome

Question 30

Sclerotome

Answer 30

Vertebrae and ribs

Question 31

Dermatome

Answer 31

Dermis of the skin

Question 32

Pharyngeal Arches

Answer 32

Pouches filled with mesoderm and neural crest cells which mature to form the face and neck.

Question 33

List events of Week 1 in chronological order.

Answer 33

Fertilization, Rapid Divisions, Morula, Blastula, and Implantation

Question 34

Bilaminar embryo, yolk sac, amnion, cyto and syncytiotrophoblast formation occur when?

Answer 34

Week 2

Question 35

What occurs during the embryonic period (Weeks 3-8)?

Answer 35

Gastrulation, Morphogenesis, and Organogenesis

Question 36

Development of the three germ layers

Answer 36

Gastrulation

Question 37

Organogenesis

Answer 37

Establishment of organ systems

Question 38

When is the period of maximum sensitivity?

Answer 38

Embryonic Period (Weeks 3 to 8)