General Embryology

Question 1

What is paracrine regulation?

Answer 1

Growth factor that acts on a cell near the manufacturing cell

Question 2

What is endocrine regulation?

Answer 2

Growth factor that travels from production cell via the blood to effector cell

Question 3

Which Growth factor plays a major role in craniofacial development?

Answer 3

BMP

Question 4

What is a transcription factor?

Answer 4

Protein that binds to a specific DNA region to control transcription

Question 5

What are the 4 main categories of transcription factors?

Answer 5

Homeodomain
Zinc finger
Basic helix-loop-helix
Winged helix

Question 6

Which genes regulate body segmentation?

Answer 6

Homeobox genes

Question 7

What are 4 examples of homeobox genes?

Answer 7

1-Hox genes:patterning the body axis
2-Msx genes:control proliferation and differentiation
3-Dlx genes:control ectodermal development
4-Sonic hedgehog genes:induction of facial primordium

Question 8

What is autocrine regulation?

Answer 8

Growth factor that acts on the same cell that produced it

Question 9

When does the preimplantation period take place?

Answer 9

First week after conception

Question 10

Non disjunction can result in what?

Answer 10

Extra chromosomes in a gamete

Question 11

What is the solid ball of cells called after initial cleavage?

Answer 11

Morula

Question 12

What does the morula turn into next?

Answer 12

Blastocyst

Question 13

Disturbances during the preimplantation period are called what?

Answer 13

Congenital malformations

Question 14

What period is known as the embryonic period?

Answer 14

Beginning of week two until end of week 8

Question 15

What are the 5 developmental processes in the embryo?

Answer 15

1-Induction
2-proliferation
3-differentiation
4-morphogenesis
5-maturation

Question 16

What is induction?

Answer 16

Action of a group of cells leading to establishment of developmental pathways in tissue

Question 17

What is proliferation?

Answer 17

Controlled cellular growth

Question 18

What is differentiation?

Answer 18

Change of embryonic cells to become distinct structurally and functionally

Question 19

What is morphogenesis?

Answer 19

Cell migration that develops into specific tissue structure

Question 20

What is maturation?

Answer 20

Process of attaining adult function

Question 21

What is a cells competence?

Answer 21

Ability to respond to induction

Question 22

What are the three germ cell layers?

Answer 22

Ectoderm
Mesoderm
Endoderm

Question 23

Which cells reorganize to for the amniotic cavity of the embryoblast?

Answer 23

Dorsal cells (epiblast layer)

Question 24

Which cells organize to form the roof of the secondary yolk sac of the embryoblast?

Answer 24

Ventral cells (hypoblast layer)

Question 25

What shape are epiblast cells?

Answer 25

High columnar

Question 26

What shape are hypoblast cells?

Answer 26

Small cuboidal

Question 27

When does the primitive streak form?

Answer 27

3rd week

Question 28

Why is the primitive streak important?

Answer 28

Critical for bilateral symmetry and germ layer formation

Question 29

What happens during gastrulation?

Answer 29

Ectodermal cells invaginate, proliferation and migrate.

Question 30

What is another name for mesoblast cells?

Answer 30

Mesenchyme

Question 31

What is the end result of gastrulation?

Answer 31

- 3 embryonic layers form - disc has cephalon end - oropharyngeal membrane is formed - stomodeum (primitive mouth)

Question 32

What do Ectodermal cells give rise to?

Answer 32

- Nervous system - hair, nails, sweat glands - epithelial lining of oral cavity - part of intraoral glands - tooth enamel

Question 33

What do endodermal cells give rise to?

Answer 33

Epithelial lining of resp and gastro tract/organs

Question 34

What do mesodermal cells give rise to?

Answer 34

Muscles and CT

Question 35

What 3 key events happen at the end of week 3?

Answer 35

1- differentiation of the nervous system 2- formation/migration of neural crest 3- embryo folding

Question 36

What is the sequence of nervous system development?

Answer 36

Neuroectoderm forms and localizes to form the neural plate which then undergoes invagination to form the neural groove

Question 37

What are the three regions of mesoderm during neural plate formation?

Answer 37

Paraxial Intermediate Lateral plate

Question 38

What does the mesodermal paraxial region become?

Answer 38

Cartilage and segmented muscle

Question 39

What does the mesodermal intermediate region become?

Answer 39

Kidneys and gonads

Question 40

What does the mesodermal lateral plate become?

Answer 40

Heart and gut

Question 41

The neural tube expands to form what?

Answer 41

Forebrain, midbrain and hindbrain (hindbrain segments into hox gene expressing rhombomeres)

Question 42

Craniofacial features are results of what?

Answer 42

Neural crest cell differentiation (nearly all tooth tissues are derived from neural crest cells)

Question 43

What happens during week 4?

Answer 43

Embryonic folding

Question 44

What time frame is considered the fetal period?

Answer 44

9th week/3rd month until 9th month

Question 45

Exposure to what can cause dental anomalies and developmental complications?

Answer 45

Teratogens

Question 46

What does the trophoblast become?

Answer 46

Placenta

Question 47

What does he primary yolk sac become?

Answer 47

Amnion

Question 48

What is characteristic of the blastocyst stage?

Answer 48

Migration of cells realignment of cells fluid filled cavity

Question 49

What is characteristic of the Morula stage?

Answer 49

Rapid proliferation

Question 50

What is notable about the 2nd and 3rd weeks of development?

Answer 50

- Formation of the trilaminar embryo - Gastrulation - Formation of the 3 germ layers

Question 51

Which adhesion molecules are calcium dependent?

Answer 51

Cadherin

Question 52

Which adhesion molecules are calcium independent?

Answer 52

CAM

Question 53

Which adhesion molecule does neuroectoderm express?

Answer 53

N-CAM

Question 54

Skin ectoderm expresses which cell adhesion molecule?

Answer 54

L-CAM