Embryology 04: Germ Layers And Tissue And Organ Differentiation: Week 3

Front 1

3 major characteristics of week 3 after fertilization

Back 1

primitive streak, notochord, 3 germ layers

Front 2

Process of forming 3 germ layers is called what?

Back 2

gastrulation

Front 3

First sign of gastrulation

Back 3

primitive streak appears caudally

Front 4

Primitive streak is made by movement of what cells medially?

Back 4

epiblast

Front 5

Mesenchyme is formed by what cells?

Back 5

epiblasts on the deep surface of the primitive streak

Front 6

Lateral mesoderm formation is induced by what signaling protein?

Back 6

TGF-B (transforming growth factor)

Front 7

Hypoblast forms what germ layer/s?

Back 7

embryonic endoderm

Front 8

Primitive streak appears in what week?

Back 8

3

Front 9

Saccrocygeal teratoma is caused by ...

Back 9

remnants of primitive streak (contains all 3 germ layers)

Front 10

Prechordal plate will give rise to ...

Back 10

oropharyngeal membrane

Front 11

The prechordal plate and cloacal membrane contain what germ layers?

Back 11

endo and ecto in direct contact (no mesoderm)

Front 12

The cardiogenic area forms more cranially or caudally on the embryo?

Back 12

cranially

Front 13

Cloacal membrane gives rise to ...

Back 13

anus

Front 14

The embryonic disc remains bilaminar at what 2 regions?

Back 14

prechordal plate and cloacal membrane. this is where endoderm and ectoderm will meet

Front 15

3 Notochord functions

Back 15

gives longitudinal axis, signals nervous development, contributes to intervertebral discs (nucleus pulposus)

Front 16

The notochord canal begins at what structure during week 3?

Back 16

primitive pit in the primitive node

Front 17

What is the notochord plate?

Back 17

flat area under notochord where there is no hypoblast

Front 18

The notochord is formed by the infolding of the ....

Back 18

notochord plate

Front 19

Notochord induces formation of _____, the primordium of the CNS?

Back 19

neural plate

Front 20

What are chordomas?

Back 20

tumors from remnants of notochord tissue

Front 21

Allantois function

Back 21

collect urine

Front 22

Allantois appears at day ...

Back 22

16

Front 23

Allantois/Urachus is seen in adults as what structure?

Back 23

median umbilical ligament

Front 24

Allantoic cysts are found where?

Back 24

between fetal umbilical vessels

Front 25

Formation of neural plate and fold is called?

Back 25

Neurulation

Front 26

Neural plate is a thickening of what cell layer?

Back 26

embryonic ectoderm, neural ectoderm

Front 27

Neural groove forms on what day?

Back 27

18

Front 28

Neural tube is formed by the end of what week?

Back 28

3

Front 29

Somatopleure is made up of what layers?

Back 29

Embryonic ectoderm and somatic mesoderm

Front 30

Splanchnopleure is made up of what layers?

Back 30

Embryonic endoderm and splanchnic mesoderm

Front 31

The somatopleure and splanchnopleure are separated by what cavity?

Back 31

intraembryonic coelom

Front 32

Somites are derived from what mesoderm?

Back 32

paraxial

Front 33

3 types of embryonic mesoderm

Back 33

paraxial, intermediate, lateral

Front 34

Somite period of human development is from what days?

Back 34

20-30

Front 35

Somites give rise to ...

Back 35

axial skeleton

Front 36

Vasculogenesis process

Back 36

mesenchymal cells become angioblasts- they aggregate to form blood islands - cavities form in the islands- angioblasts flatten and make endothelium- cavities fuse to make vessels

Front 37

Mesenchyme is derived form what germ layer?

Back 37

mesoderm

Front 38

Vasculognesis occurs during what week?

Back 38

3

Front 39

Hematogenesis occurs during what week?

Back 39

5

Front 40

First heart beats are seen on what day?

Back 40

21/22

Front 41

First organ to reach functional state?

Back 41

heart

Front 42

fertilization of an empty oocyte by 1 sperm leads to what?

Back 42

Complete hyatidiform mole

Front 43

fertilization of an empty oocyte by 2 sperms leads to what?

Back 43

partial hyatidiform mole

Front 44

Hyatidiform moles are caused by swelling of what?

Back 44

Degenerating chorionic villi

Front 45

5% of hyatidiform moles develop into ...

Back 45

chorocarcinomas

Front 46

primary chorionic villi arise in what week?

Back 46

end of week 2

Front 47

secondary chorionic villi arise in what week?

Back 47

early week 3

Front 48

Blood flows through the tertiary chorionic villi at what time?

Back 48

by end of third week

Front 49

The tertiary chorionic villi are surrounded by what structure?

Back 49

cytotrophoblastic shell

Front 50

stem chorionic villi means ...

Back 50

they are anchoring villi

Front 51

branch chorionic villi means ...

Back 51

they are mostly for gas exchange