Development with Neurulation, Folding, and Body Cavities

Question 1

Organogenesis occurs when?

Answer 1

Week 3-8

Question 2

What is Organogenesis?

Answer 2

When the primary germ layers give rise to tissues and organs

Question 3

Define Neurulation

Answer 3

Process by which the neural plate forms the neural tube

Question 4

Where does neurulation occur and via what process?

Answer 4

In the ectoderm via notochordal inducation

Question 5

What are the 4 main events in neurulation?

Answer 5

1. Formation of neural plate
2. Shaping of neural plate
3. Invagination of neural plate
4. Closure of neural groove

Question 6

What is the neural plate?

Answer 6

A thickening in overlying ectoderm along the midline of the embryo

Question 7

What are the neural folds?

Answer 7

Laterally elevated edges of the neural plate

Question 8

What is the neural groove?

Answer 8

Depressed midregion of neural plate

Question 9

How is the neural tube formed?

Answer 9

Neural folds begin to move together and eventually fuse

Question 10

How does the fusion of the neural folds progress?

Answer 10

Both cranially and caudally

Question 11

Where is the neural tube located?

Answer 11

Under the surface ectoderm

Question 12

The neural groove will eventually become what?

Answer 12

The neural canal

Question 13

The final opening on the cranial end during neural tube closure is called what?

Answer 13

The cranial neuropore

Question 14

When does the cranial neuropore close?

Answer 14

Day 25

Question 15

The final opening on the caudal end during neural tube close is called what?

Answer 15

The caudal neuropore

Question 16

When does the caudal neuropore close?

Answer 16

Day 27

Question 17

What does the closing of the caudal neuropore signal?

Answer 17

The end of neurulation

Question 18

What are neural crest cells?

Answer 18

Cells at the lateral border (crest) of the neuroectoderm when neural folds fuse

Question 19

What kind of transition do neural crest cells undergo?

Answer 19

Epithelial-to-mesenchymal transition

Question 20

After their epithelial-to-mesenchymal transition, where do the neural crest cells go?

Answer 20

The underlying mesoderm

Question 21

What 3 parts does the mesoderm differentiate into?

Answer 21

Paraxial mesoderm, Lateral plate mesoderm, and Intermediate mesoderm

Question 22

What is the paraxial mesoderm?

Answer 22

Mesoderm near midline that becomes thicker

Question 23

What is the lateral plate mesoderm?

Answer 23

Thin mesoderm that is more lateral

Question 24

What is the intermediate mesoderm?

Answer 24

The mesoderm between the paraxial and lateral plate mesoderm.

Question 25

Lateral plate mesoderm is eventually split into?

Answer 25

Somatic (parietal) and Splanchnic (visceral)

Question 26

What does the somatic mesoderm line?

Answer 26

The amnion

Question 27

What does the splanchnic mesoderm line?

Answer 27

The yolk sac

Question 28

The cavity between the somatic and splanchnic mesoderm is called what?

Answer 28

The intraembryonic cavity

Question 29

The paraxial mesoderm eventually organizes into segments called what?

Answer 29

Somites

Question 30

Somites form in which direction?

Answer 30

Cranially --> Caudally

Question 31

How do somites appear?

Answer 31

In pairs

Question 32

The somites eventually give rise to (3)

Answer 32

Axial skeleton, skeletal muscles, and the dermis of the back

Question 33

What can you determine by counting the somites?

Answer 33

The age of the embryo

Question 34

What do they mesoderm cells do when they originally differentiate?

Answer 34

They go through epithelialization and arrange in a donut shape around small lumen

Question 35

Where do cells in the ventral and medial walls shift to?

Answer 35

They shift to surround the neural tube

Question 36

What do ventral and medial cells create when they shift to surround the neural tube?

Answer 36

Sclerotome

Question 37

Where do dorsomedial and ventrolateral cells form?

Answer 37

Dermatome

Question 38

What do some of the dermatome cells eventually become when they migrate beneath the dermatome?

Answer 38

Myotome

Question 39

What does the Sclerotome form?

Answer 39

Vertebrae and ribs

Question 40

What does the Dermatome form?

Answer 40

Dermis

Question 41

What does the Myotome form?

Answer 41

Muscles

Question 42

What does the Intermediate Mesoderm differentiate into?

Answer 42

The urinary and reproductive system

Question 43

What forms the lateral body wall folds?

Answer 43

Parietal mesoderm layer along with overlying ectoderm

Question 44

What does the lateral body wall fold help to close?

Answer 44

The ventral body wall

Question 45

What forms the mesothelial membranes (serous membranes)

Answer 45

Mesoderm cells of the parietal layer surrounding the intraembryonic cavity

Question 46

What do serous membranes line?

Answer 46

The pritoneal, pleural, and pericardial cavities

Question 47

What forms the walls of the gut tube?

Answer 47

Visceral mesoderm layer together with endoderm

Question 48

What do the mesoderm cells of the visceral layer form?

Answer 48

Thin serous membranes around each organ

Question 49

The endoderm will eventually differentiate into what?

Answer 49

The GI tract

Question 50

Endoderm derivates line the ___ surface of the embryo and forms the roof of the ___ ___

Answer 50

Ventral, yolk sac

Question 51

What happens simultaneously in both the sagittal plane (cranial/caudal) the the horizontal plane (lateral)?

Answer 51

Folding

Question 52

What acts as a hinge in cranial folding?

Answer 52

The oropharyngeal membrane

Question 53

In cranial folding, what does part of the yolk sac endoderm become?

Answer 53

The foregut (proximal part of GI)

Question 54

When does the oropharyngeal membrane rupture and why?

Answer 54

It ruptures around day 26 to form the mouth

Question 55

In caudal folding, what acts as a hinge?

Answer 55

The cloacal membrane

Question 56

In caudal folding, what does part of the yolk sac endoderm become?

Answer 56

The hindgut (distal part of GI)

Question 57

What happens to the connecting stalk during caudal folding?

Answer 57

It attaches to the ventral aspect of the embryo

Question 58

In lateral folding, what is the dorsal part of the yolk sac endoderm incorporated as?

Answer 58

The embryonic midgut

Question 59

By the end of week 4, all lateral folds are fused except for what region?

Answer 59

The region of the connecting stalk

Question 60

The midgut connection to the yolk sac constricts, leaving a narrower connection called what?

Answer 60

The omphaloenteric duct (vitelline duct)

Question 61

Where are the parietal and visceral layer of serous membranes continuous at?

Answer 61

The dorsal mesentery

Question 62

What does the dorsal mesentery do?

Answer 62

Suspends the gut tube from the posterior body wall into the peritoneal cavity

Question 63

What does the ventral mesentery result from?

Answer 63

Thinning of the septum transversum

Question 64

What are the boundaries of the ventral mesentery?

Answer 64

Caudal foregut to upper part of the duodenum

Question 65

What 3 things make up the embryonic body cavity?

Answer 65

Pericardial cavity, 2 pericardioperitoneal canals, and a peritoneal cavity

Question 66

What is the septum transversum?

Answer 66

The mesoderm between the thoracic cavity and the yolk sac

Question 67

Does the septum transversum separate the thoracic and abdominal cavities completely and why?

Answer 67

No: 2 pericardioperitoneal canals

Question 68

As lung buds grow, what do they expand into?

Answer 68

Pericardioperitoneal canals

Question 69

In what direction do pleuropericardial folds grow?

Answer 69

Laterally --> Medially

Question 70

What do pleuropericardial folds divide the pericardial cavity into?

Answer 70

A definitive pericardial (1) and pleural cavities (2)

Question 71

What are the 4 components of the diaphram?

Answer 71

Septum transversum, Pleuroperitoneal membranes, Mesentery of esophagus, and Body wall mesoderm