Body Cavities And body Folding

Question 1

What defines Growth as a phase of embryonic development?

Answer 1

Cell division and elaboration of cell products

Question 2

What defines Morphogenesis as a phase of embryonic development ?

Answer 2

Development of f shape, size and other features of a particular organ or part of whole body

Question 3

How is Morphogenesis controlled?

What changes will this lead to?

Answer 3

Controlled by gene expression and regulation in an orderly sequence

Changes in

• cell fate
• cell shape
• cell movement

Question 4

What does Morphogenesis allow fo?

Answer 4

Allows cells to interact w/ each other during the formation of tissues and organs

Question 5

What defines Differentiation as a phase of embryonic development?

Answer 5

Organization of cells into a precise pattern of tissues and organs capable of performing specialized functions

Question 6

What will form the primordium of the intraembryonic coelom?

Answer 6

Isolated coelomic spaces int he lateral plate and cardiogenic mesoderm

Question 7

What is a coelom?

Answer 7

Embryonic body cavity

Question 8

How is the intraembryonic coelom formed?

What shape does this take on?

Answer 8

Thru the coalescing of isolating coelomic spaces

Horseshoe shaped

Question 9

What will the formation of the Itnraembyronic coelom do tot he Lateral mesoderm?

Answer 9

Divides lateral mesoderm into

1. Somatic/parietal layer of lateral mesoderm
2. Splanchnic/visceral layer of lateral mesoderm

Question 10

What is the somatic layer of lateral mesoderm continuous w/ ?

Answer 10

Continuous w/ extra-embryonic mesoderm covering the amnion

Question 11

What is the splanchnic layer of the lateral mesoderm continuous w/?

Answer 11

W/ extra-embryonic mesoderm covering the umbilical vesicle

Question 12

What is somatopleure?

What doe this form?

Answer 12

Somatic mesoderm and overlying embryonic ectoderm

forms the body wall

Question 13

What is splanchopleure?

What will it form?

Answer 13

Splanchnic mesoderm and underlying embryonic endoderm

forms embryonic gut

Question 14

How does folding in the embryonic planes occur?

Answer 14

Folding in cranial and caudal and sides simultaneously

Question 15

What does the body folding of the embryonic in the median and horizontal planes do?

Answer 15

Takes flat,trilaminar embryonic disc
—>

Cylindrical embryo

Question 16

Does folding occur faster laterally or in the median plane?

Answer 16

Lateral edges do not keep pace w/ the increase in embryo length

Question 17

What day does the head fold begin?

Answer 17

Day 22/week 4

Question 18

How does Head Folding occur?

Answer 18

1. Embryo elongates in length
2. Neural folds grow over the oropharyngeal membrane
3. This moves the septum transversum, primordial heart, pericardial coelom and oropharyngeal membrane to ventral (front) surface
4. Part of endoderm of umbilical vesicle is incorporated as foregut

Question 19

What comprises the foregut?

Answer 19

Primordium of pharynx, esophagus, and lower respiratory system

Question 20

After head folding, how is the intra-embryonic coelom?

Answer 20

Pericardial cavity is at front

Pericardioperitoneal canal run dorsally on each side of foregut

Intraembryonic and extraembryonic coelom are in communication

Question 21

What is the process of tail folding?

Answer 21

1. Caudal (back) end of embryonic folds in due to growth of distal neural tube
   Forms the spinal cord primordium
2. Caudal eminence projects over the cloacal membrane
3. Part of endoderm from Allantois will form hindgut
4. Terminal hindgut dilates to form the cloaca

Question 22

What is the future of the cloacal membrane?

Answer 22

To form the anus

Question 23

What comprises the hindgut?

Answer 23

Descending colon/rectum

Question 24

What is the cloaca?

Answer 24

Rudiment of urinary bladder/rectum

Question 25

Before tail folding where did the primitive streak lie? After folding?

Answer 25

Before: primitive streak lies cranial to cloacal membrane After: lies caudal to cloacal membrane

Question 26

What is the allantois/

Answer 26

Diverticulum of the umbilical vesicle

Question 27

What produces the right and left lateral folds?

Answer 27

Rapid growth of SC and smites

Question 28

What happens when the lateral fold extend ventrally toward midline

Answer 28

Creates a cylindrical embryo Abdominal walls forms and incorporates ENDOderm to form midgut Omphaloentric duct is formed

Question 29

How is the omphaloenterifc duct formed?

Answer 29

By reducing the connection b/w the umbilication vesicle and midgut

Question 30

What happens as the umbilical cord forms?

Answer 30

Communication between the intraembryonic and extra-embryonic coelomic cavities narrows

Question 31

What will eventually obliterate most of the extraembryonic coelom?

Answer 31

Expansion of the amniotic cavity

Question 32

What does the amnion form for the umbilical cord?

Answer 32

Forms epithelial covering

Question 33

What is the intraembryonic coelom divided into?

Answer 33

Pericardial cavity Pleural cavities Peritoneal cavity

Question 34

What are the cavities of the intraembryonic coelom lined with?

Answer 34

With mesothelium - parietal walls from somatic mesoderm - visceral wall from splanchnic mesoderm

Question 35

How do head folds reshape the intraembryonic coelom re: Pericardial cavity?

Answer 35

Pericardial cavity.. moved ventrally and anterior to foregut and above septum transversum (heart will reposition itself into this cavity) opened into peri-cardio-peritoneal canals lateral to foregut

Question 36

What is the function of the pericardioperitoneal canals?

Answer 36

Connect pericardial cavity tot he peritoneal cavity

Question 37

How do head folds reshapes the intraembryonic coelom re: Peritoneal cavity?

Answer 37

Relocated so IE and EE coeloms are continuous f

Question 38

What is suspended in the peritoneal cavity and how?

Answer 38

Caudal foregut, midgut, and hindgut are suspended by dorsal mesentery

Question 39

What is the septum transversum?

Answer 39

Primordium of the central tendon of diaphragm

Question 40

How do partitions form in the pericardioperitoneal canals?

Answer 40

Partitions form due to growth of primordial lounges

Question 41

What are the 2 folds found in each pericardial peritoneal canal?

Answer 41

Pleuro-pericardial folds Pleuro-peritoneal folds

Question 42

What is the function of pleuro-pericardial folds?

Answer 42

Separate head from lungs

Question 43

Where do pleuro-pericardial folds develop in the pericardial-peritoneal canals?

Answer 43

Develop above developing lungs

Question 44

What will the pleuro-pericardial folds form upon enlargement?

Answer 44

Form pleuropericardial membranes

Question 45

How do the pericardial cavities and 2 pleural cavities become separated? When do they become separate?

Answer 45

Pleuropericardial membranes fuse w/ mesenchyme in front of esophagus Week 7

Question 46

What will grow into he pericardioperitoneal canals? What will this cause?

Answer 46

Bronchial buds Will cause cavity to expand and mesenchyme to split

Question 47

What will the growing bronchial buds cause mesenchyme to split into?

Answer 47

Outer layer —> thoracic wall Inner layer —> fibrous pericardium (outerlayer of pericardial sac)

Question 48

What do the pleuroperidaial folds form form and where?

Answer 48

From somatic layer of the lateral plate mesoderm (somatic = parietal) On lateral body wall

Question 49

How many layers do the pleuropericardial folds have?

Answer 49

3 layers Epithelia-mesenchym-epithelie

Question 50

How is the primordial diaphragm formed?

Answer 50

Pleuroperitoneal membrane fuses with the dorsal mesentery of esophagus and septum transversum

Question 51

What forms the central tendon of the diaphragm?

Answer 51

Expansion of the septum transversum and subsequent fusion w/ the dorsal mesentery of the esophagus and Pleuroperitoneal membranes

Question 52

What is the dorsal mesentery?

Answer 52

Median portion of diaphragm

Question 53

How is the Crura of the diaphragm formed?

Answer 53

From myoblasts growing into the dorsal mesentery

Question 54

What is the innervation of the diaphragm? Why?

Answer 54

As myoblasts migrated into the dorsal mesentery it pulled ventral rami C3-C5 with them They passed thru pleuroperidarical membranes —> Phrenic n. Lies on fibrous pericardium

Question 55

What is Gastroschisis?

Answer 55

Protrusion of viscera; site of abdominal defect to right of umbilical cord rather than midline

Question 56

How common is gastroschisis?

Answer 56

1 in 3000 live births

Question 57

How is Gastroschisis different from an umbilical hernia?

Answer 57

Bowel is uncovered and floating in amniotic fluid

Question 58

Why does Gastroschisis occur?

Answer 58

Results from failure of the lateral body folds to fuse complete when the anterior abdominal wall forms

Question 59

When does the anteiror abdominal wall form?

Answer 59

4th week

Question 60

What is a congenital Epigastric hernia?

Answer 60

Midline bulge of abdominal wall located b/w the xyphoid process and umbilicius Bowel is not exposed to amniotic fluid; remained covered by skin and subcutaneous tissues

Question 61

What is Congenital Diaphragmatic hernia? (CDH)

Answer 61

A posterolateral defect where viscera bulge into the plural cavity

Question 62

What is the occurrence of Congenital diaphragmatic hernias?

Answer 62

1 in 2200 live births

Question 63

What can cause Congenital DIaphragmatic hernias?

Answer 63

-improper closure of body cavities -open left canal bc of lack of myoblasts migrating into the pericardioperitoneal canals/membrane (Right closes before left, so usually left is affected)

Question 64

What are some consequences of a Congenital Diaphragmatic Hernia? Which side is typically affected more?

Answer 64

Delayed lung maturation Polyhydramnios Left side affected 80% of time