Body from Zygote to Embryo

Question 1

3 developmental periods

Answer 1

Pre-embryonic period
Embryonic period (all major organ systems form)
Fetal period

Question 2

2 major things that happen in week 1

Answer 2

Fertilization

Cleavage

Question 3

Fertilization most often happens in the…

Answer 3

Ampulla of the uterine tube

Question 4

Blastomeres

Answer 4

Small cells that result from mitotic cleavage of the zygote

Question 5

Morula

Answer 5

Ball of 12-32 blastomeres

Between zygote and blastocyst stage

Question 6

Zona pellucida

Answer 6

Glycoprotein coat that surrounds developing embryo

Prevents polyspermy

Question 7

2 parts of the blastocyst

Answer 7

Inner cell mass/embryoblast

Trophoblasts

Question 8

What happens when the blastocyst “hatches”?

Answer 8

It begins to implant into the uterine wall

Question 9

2 main things that happen in week 2

Answer 9

Implantation

Bilaminar embryonic disc formation

Question 10

The inner cell mass forms a disc with 2 cavities…

Answer 10

Upper cavity is the amniotic cavity

Lower cavity is the yolk sac/umbilical vesicle

Question 11

Yolk sac

Answer 11

Provides germ cells

Early site of blood cell production

Question 12

2 layers of bilaminar disc

Answer 12

Epiblasts

Hypoblasts

Question 13

What cells produce hCG

Answer 13

Trophoblasts

Question 14

What main thing happens in week 3

Answer 14

Gastrulation (formation of the 3 primary germ layers)

Question 15

Primitive streak

Answer 15

At the caudal end of the embryo
Epiblasts proliferate and migrate medially to form the streak
It lengthens by addition of cells at the caudal end

Question 16

All 3 primary germ layers originate from…

Answer 16

Epiblasts!

Endoderm does NOT come from hypoblasts

Question 17

2 locations where mesoderm does not migrate

Answer 17

Prechordal plate (future mouth)
Cloacal plate (future anus)

Question 18

Primitive node and pit

Answer 18

Form at the cranial end of the primitive streak

Organizing center for notochord mesoderm

Question 19

Notochord

Answer 19

From mesoderm

Key organizing centre for neurulation

Question 20

Ectoderm becomes…

Answer 20

Nervous sytem
Epidermis of skin
Teeth
Etc

Question 21

Mesoderm becomes…

Answer 21

Muscles
Bone
Cartilage
Blood cells and vessels
Dermis of skin
Kidneys
Ureters
Genital system
Etc

Question 22

Endoderm becomes…

Answer 22

Lining of GI tract
Liver
Pancreas (except islets)
Lining of respiratory tract
Bladder
Etc

Question 23

3 things that happen in late week 3 to late week 4

Answer 23

Neurulation
Somite Formation
Coelom Formation

Question 24

Neurulation

Answer 24

Formation of the neural tube (future CNS)

Question 25

Function of the notochord

Answer 25

Induces overlying ectoderm to thicken and form a neural plate
Neural plate eventually forms neural tube, which zips up from both ends

Question 26

Somites

Answer 26

2 blocks of mesoderm on either side of the notochord

Become axial skeleton, associated musculature, and dermis

Question 27

Coelom formation

Answer 27

Formation of the body cavities (pericardial, pleural, and peritoneal coeloms)

Question 28

What is the
1. future heart
2. future diaphragm
called?

Answer 28

1. Cardiogenic area

2. Septum transversum

Question 29

What is the main thing that happens in week 4?

Answer 29

Body folding

Question 30

Somatic vs splanchnic mesoderm

Answer 30

Somatic stays with the body wall

Splanchnic goes with gut

Question 31

What does the lateral mesoderm become?

Answer 31

Coelom

Question 32

What does the intermediate mesoderm become?

Answer 32

Urinary system

Question 33

Neural crest cells become…

Answer 33

Parts of the peripheral NS