Embryology

Question 1

What is another name for the inner cell mass?

Answer 1

Embryoblast

Question 2

What is another name for the outer cell mass?

Answer 2

Trophoblast

Question 3

What is the beginning of implantation?

Answer 3

When the blastocyst attaches to the endometrial epithelium at the embryonic pole

Question 4

What 2 layers does the trophoblast give rise to?

Answer 4

1) Cytotrophoblast

2) Syncytiotrophoblast

Question 5

What is the new layer of cells that form on the surface of the inner cell mass at the end of the first week?

Answer 5

Hypoblast

Question 6

By what day(s), is implantation complete by?

Answer 6

11-12

Question 7

When can primary villi first be seen?

Answer 7

9 days

Question 8

When can secondary villi be seen?

Answer 8

11-12 days

Question 9

Where does implantation normally occur?

Answer 9

Posterior wall of the uterus

Question 10

How often do ectopic pregnancies occur?

Answer 10

.25-1%

Question 11

Where is the most likely place for ectopic pregnancies?

Answer 11

Within the uterine tube

Question 12

What hormone when giving in large doses prevents preganancies from occurring by 1) inhibiting implantation b/c the uterus isn’t ready 2) delaying ovulation 3) inhibiting ovulation 4) preventing fertilization?

Answer 12

Progestin compounds

Question 13

At what day is there an advanced morula?

Answer 13

4 days

Question 14

At what day is there a blastocyst?

Answer 14

5 days

Question 15

What is a transgenic mouse?

Answer 15

Created by injecting the pronucleus with a DNA fragment that then becomes RANDOMLY incorporated into the cell’s genome

Question 16

What is a gene-targeted mouse?

Answer 16

Created by constructing the DNA fragment in a way that the gene is not only incorporated into the genome but also replaces part of the endogenous gene that matches specific regions of the DNA fragment. “Transfection”

Question 17

The inner cell mass/embryoblast forms these 2 things?

Answer 17

1) Epiblast

2) Hypoblast

Question 18

Cells from the yolk sac endoderm and the primitive streak give rise to?

Answer 18

Extraembryonic mesoderm (surrounds the amnion and yolk sac)

Question 19

What cavities are formed from the syncytiotrophoblast invading the endometrial stroma?

Answer 19

Amniotic and chorionic cavities

Question 20

What is another term for the hypoblast?

Answer 20

Bilaminar embryonic disc

Question 21

What cells begin to produce hCG?

Answer 21

Syncytiotrophoblast cells

Question 22

Where do lacunae appear?

Answer 22

Syncytiotrophoblast

Question 23

At early stages in development, how do nutrients pass to the embryonic disc?

Answer 23

Diffusion

Question 24

At what day is the conceptus completely embedded in the endometrium?

Answer 24

Day 10

Question 25

What days are the lacunar networks establishing the primitive uteroplacental circulation?

Answer 25

12-12.5

Question 26

The extraembryonic coelom splits the extraembryonic mesoderm into:

Answer 26

1) Somatic Mesoderm | 2) Splanchnic mesoderm

Question 27

Where do primary villi originate from?

Answer 27

Cytotrophoblast and induced by extraembryonic somatic mesoderm

Question 28

What 2 layers constitue the chorion?

Answer 28

1) Extraembryonic somatic mesoderm | 2) 2 layers of the trophoblast

Question 29

At day 13, what develops from the hypoblast cells?

Answer 29

Prechordal plate

Question 30

The prechordal plate is the future site of what?

Answer 30

1) Mouth | 2) (Important organizer of the head)

Question 31

When can hCG be assayed in the blood?

Answer 31

Day 8 post fertilization

Question 32

When can hCG be assayed in the urine?

Answer 32

Day 10 post fertilization

Question 33

High HcG levels can suggest?

Answer 33

1) multiple pregnancies 2) hydatidiform mole 3) gestational trophoblastic neoplasia

Question 34

What are the 2 forms of hydatidiform moles?

Answer 34

1) Complete | 2) Partial

Question 35

What is a complete hydatidiform mole?

Answer 35

1) Trophoblast develops over embryoblast 2) Pregnancy without embryo 3) Placental villi become swollen/vesicular 4) trophoblastic tissue high level of hCG 5) Diploid embryo but all parental 6) female pronucleus lost or absent 7) polyspermia 8) diploid sperm Pregnancy spontaneously aborted

Question 36

What is a partial hydatidifrom mole?

Answer 36

Usually some evidence of embryonic development 1) Triploidy (dbl dose of paternal, polyspermia, diploid sperm) Typically spontaneously abort

Question 37

What is the main difference btw a complete vs partial hydatidiform mole?

Answer 37

Partial H. moles have some evidence of embryonic development.

Question 38

What is gastrulation?

Answer 38

Process by which the bilaminar embryonic disc (hypoblast) is converted into a trilaminar embryonic disk

Question 39

What does gastrulation MARK?

Answer 39

morphogenesis

Question 40

Gastrulation begins with the formation of?

Answer 40

The primitive streak at caudal end

Question 41

This process and what cell type result in the 3 germ layers?

Answer 41

Gastrulation; epiblast

Question 42

During gastrulation the cells of the epiblast undergo this type of transformatios?

Answer 42

Epithelial-mesenchymal transformation invaginating btw the epiblast and hypblast all along primitive streak DAY 16

Question 43

This develops from invaginating mesenchymal cells along the central axis of the embryonic disk?

Answer 43

notochordal process

Question 44

What is forming in all direction from the primitive streak?

Answer 44

mesoderm

Question 45

From gastrulation, the primitive streak actively forms what until the early 4th week and diminishes by the end of the 4th week?

Answer 45

Mesenchyme

Question 46

What forms the neural plate?

Answer 46

Ectoderm

Question 47

What are the functions of the notocord?

Answer 47

1) Primordial axis-ridigity 2) basis for axial skeleton 3) future site of vertebral bodies 4) induces overlying ectoderm and form neural plate 5) forms the nucleus pulposus in the adult 6) specifies cells in the ventral aspect of neural tube Notocord: condensed group of mesenchymal cells

Question 48

What is the process of neuralation?

Answer 48

Formation of the neural plate and neural folds and closure of these folds to form the neural plate (neuralectoderm)

Question 49

The neural plate gives rise to what?

Answer 49

The CNS: brain and spinal cord

Question 50

What are the 1st signs of brain development?

Answer 50

Neural groove and lateral neural folds in the neural plate

Question 51

These structures fuse to form the neural tube?

Answer 51

Neural folds

Question 52

These cells that arise from neuroectodermal cells migrate on either side of the neural fold to form the sensory ganglia of the spinal and cranial nerves?

Answer 52

Neural crest cells

Question 53

As neuralation is taking place, the paraxial, intermediate, and lateral mesoderm forms from what?

Answer 53

Intraembryonic mesoderm

Question 54

The paraxial mesoderm gives rise to?

Answer 54

Somites

Question 55

What days are the somite period of development?

Answer 55

20 to 30

Question 56

The somites give rise to?

Answer 56

1) Axial skeleton (e.g. bones ribs, sternum) 2) Associated axial skeleton musculature 3) Adjacent dermis

Question 57

At day 24 of development, the condensed mesechyme differentiates into what 2 structures?

Answer 57

1) Dermomyotome | 2) Sclerotome

Question 58

The dermomyotome by day 26 gives rise to ?

Answer 58

Dermotome and myotome

Question 59

The dermotome gives rise to?

Answer 59

Dermis

Question 60

The myotome gives rise to?

Answer 60

Myoblasts that give rise to muscle

Question 61

The sclerotome gives rise to?

Answer 61

Axial skeleton

Question 62

The intermediate mesoderm gives rise to?

Answer 62

Urogenital system

Question 63

What 2 regions are the lateral plate mesoderm divided into?

Answer 63

1) Somatic mesoderm | 2) Splanchnic mesoderm

Question 64

The somatic mesoderm and the overlying ectoderm are referred to as?

Answer 64

Somatopleure

Question 65

The Somatopleure form what structure?

Answer 65

Embryonic body wall

Question 66

The splanchnic mesoderm and the underyling endoderm are referred to as?

Answer 66

Splanchonopleure

Question 67

Splanchonopleure forms what strucutre?

Answer 67

1) Embryonic guy wall | 2) Cardiovascular system HEART

Question 68

When do the intraembryonic and extraembryonic coelom begin to form?

Answer 68

Days 21-28 (week 4)

Question 69

The intraembryonic coelom divides the lateral mesoderm into two layers?

Answer 69

1) Parietal/intraembryonic somatic mesoderm | 2) Visceral or intraembryonic splanchnic mesoderm

Question 70

What 3 structures does the intraembryonic coelom ultimately form?

Answer 70

1) Pericardial cavity 2) Pleural cavity 3) Peritoneal cavity

Question 71

When does the cardiovascular system begin to develop (blood islands/blood vessels)?

Answer 71

17 days or 3rd week

Question 72

Where does the cardiovascular system formation occur from (formation of extraembryonic blood islands)?

Answer 72

Extraembryonic mesoderm of the yolk sac, connecting stalk, and chorion

Question 73

This is the formation of blood vessels from hemangioblasts, cells that have differentiated from the splanchnopleuric mesoderm?

Answer 73

Vasculogenesis

Question 74

Blood islands to epithelium is what kind of transformation?

Answer 74

Mesechemal to Epithelial

Question 75

What is angiogenesis?

Answer 75

Budding and sprouting of new vessels from exisitng angioblastic cords.

Question 76

What original structure is the heart descended from?

Answer 76

Cardiogenic plate or crescent which represents the primary heart field

Question 77

Does the early embryonic heart have chambers?

Answer 77

No

Question 78

What day is the heart forming around?

Answer 78

20 days (3rd week)

Question 79

What day does the heart start to beat?

Answer 79

22 days (immediately after the heart tube forms)

Question 80

When does blood formation in the embryo begin?

Answer 80

Weeks 5-6

Question 81

What does embryonic blood form from?

Answer 81

Mesoderm chiefly in liver, spleen bone marrow, and lymph nodes

Question 82

Mesenchymal cells that surround the primordial blood vessels differentiate into what structure(s)?

Answer 82

Muscular and connective tissue elements of the vessels.