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Flashcards in Body from Zygote to Embryo Deck (33)
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1

3 developmental periods

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

2

2 major things that happen in week 1

Fertilization
Cleavage

3

Fertilization most often happens in the...

Ampulla of the uterine tube

4

Blastomeres

Small cells that result from mitotic cleavage of the zygote

5

Morula

Ball of 12-32 blastomeres
Between zygote and blastocyst stage

6

Zona pellucida

Glycoprotein coat that surrounds developing embryo
Prevents polyspermy

7

2 parts of the blastocyst

Inner cell mass/embryoblast
Trophoblasts

8

What happens when the blastocyst "hatches"?

It begins to implant into the uterine wall

9

2 main things that happen in week 2

Implantation
Bilaminar embryonic disc formation

10

The inner cell mass forms a disc with 2 cavities...

Upper cavity is the amniotic cavity
Lower cavity is the yolk sac/umbilical vesicle

11

Yolk sac

Provides germ cells
Early site of blood cell production

12

2 layers of bilaminar disc

Epiblasts
Hypoblasts

13

What cells produce hCG

Trophoblasts

14

What main thing happens in week 3

Gastrulation (formation of the 3 primary germ layers)

15

Primitive streak

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

16

All 3 primary germ layers originate from...

Epiblasts!
Endoderm does NOT come from hypoblasts

17

2 locations where mesoderm does not migrate

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

18

Primitive node and pit

Form at the cranial end of the primitive streak
Organizing center for notochord mesoderm

19

Notochord

From mesoderm
Key organizing centre for neurulation

20

Ectoderm becomes...

Nervous sytem
Epidermis of skin
Teeth
Etc

21

Mesoderm becomes...

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

22

Endoderm becomes...

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

23

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

Neurulation
Somite Formation
Coelom Formation

24

Neurulation

Formation of the neural tube (future CNS)

25

Function of the notochord

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

26

Somites

2 blocks of mesoderm on either side of the notochord
Become axial skeleton, associated musculature, and dermis

27

Coelom formation

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

28

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

1. Cardiogenic area
2. Septum transversum

29

What is the main thing that happens in week 4?

Body folding

30

Somatic vs splanchnic mesoderm

Somatic stays with the body wall
Splanchnic goes with gut