CP Formation of the Body Cavities

Question 1

Early in the fourth week, where is the septum transversum relative to the developing heart?

How does it end up below the heart?

Answer 1

The septum transversum is rostral to the heart

Longitudinal (Median) folding pushes the septum transversum down and under the heart.

Question 2

What are the relative locations of the septum transversum, heart, and oropharyngeal membrane in the late fourth week?

Answer 2

Anterior to posterior:

Oropharyngeal Membrane,

Heart,

Septum Transversum

Question 3

What structures are overgrown by the tail fold?

Answer 3

The cloaca and the connecting stalk

Question 4

What is the splanchnopleura made of?

Answer 4

Splanchnic layer of the lateral plate mesoderm

Endoderm making up the yolk sac

Question 5

What is the somatopleura made of?

Answer 5

Somatic lateral plate mesoderm

Ectoderm surrounding embryonic cavity

Question 6

Which pleura comes from the somatic layer of the lateral plate mesoderm?

Answer 6

Parietal pleura

(Soma means body, the parietal side is on the body wall)

Question 7

Which pleura comes from the splanchnic layer of the lateral plate mesoderm?

Answer 7

Visceral pleura

Splanchnicus in modern latin means “entrails,” and viscus means “organs.” They go together.

Question 8

In what disease is the heart found outside the body after birth?

Answer 8

Ectopia Cordis

Question 9

What are the four major symptoms of Ectopia Cordis?

Answer 9

Heart outside the body

No pericardium

Bifed sternum

Death

Question 10

What embryonic layer do the pleuroperitoneal and pleuropericardial folds come from?

Answer 10

Somatic layer of the lateral plate mesoderm

Question 11

What separates the pericardial cavity from the peritoneal cavity?

Answer 11

The septum transversum and the pleuroperitoneal membrane coming together to form the thoracic diaphragm.

Question 12

What does the dorsal mesentary of the esophagus give rise to in the thoracic diaphragm?

Answer 12

The crura

Question 13

What does the septum transversum give rise to in the thoracic diaphragm?

Answer 13

The central tendon

Question 14

The intraembryonic coelom divides the lateral mesoderm into what two structures?

Answer 14

somatic layer of lateral mesoderm

splanchnic layer of lateral mesoderm

Question 15

The somatic layer of lateral mesoderm is continuous with what?

The splanchnic layer of lateral mesoderm is continuous with what?

Answer 15

the extraembryonic mesoderm covering amnion

the extraembryonic mesoderm covering umbilical vesicle

Question 16

The somatopleure is made of what and forms what?

the splanchnopleure is made of what and forms what?

Answer 16

somatic mesoderm and embryonic ectoderm

forms body wall

splanichnic mesoderm and embryonic endoderm

forms embryonic gut

Question 17

What are the steps of embryonic head folding?

Answer 17

1. embryo elongates cranially and caudally (wk4)
2. Neural folds project dorsally and overgrow oropharyngeal membrane
3. Overgrowth moves septum transversum, primordial heart, pericardial coelom, and oropharyngeal membrane to ventral surface
4. part of the endoderm of the umbilical vesicle is incorporated as the foregut

Question 18

What structures/compartments are present after head folding ?

Answer 18

• pericardial cavity is ventral​
• pericardioperitoneal canals run dorsally on each side of the forgut
• intraembryonic and extraembryonic coeloms are in communication

Question 19

What structures move during tail folding?

how does this affect the primitive streak?

Answer 19

caudal eminence prjects over cloacal membrane and will form hindgut (from endoderm) and cloaca

primitive streak lies craninal to cloacal before folding, after folding it lies caudal

Question 20

What is the process of lateral folding and what is formed as a result

Answer 20

SC and somites grow rapidly, causing lateral folds to form and fuse forming a cylinder

midgut forms as well as the omphaloenteric duct between the umbilical vesicle and the midgut, amniotic cavity expands, reducing extremebryonic coelom

Question 21

What is gastroschisis?

what is congenital epigastric hernia?

Answer 21

protrustion of viscera such that it is exposed to amniotic fluid, typically right of umbilical cord

bulge of abdominal wall between xiphoid and umbilicus, not exposed like gastroschisis

Question 22

What are the three divisions of the intraembryonic coelom?

Answer 22

pericardial cavity

pleural cavities

peritoneal cavity

Question 23

After head folding where are the following structures located?

pericardial cavity:

pericardioperitoneal canals

perinoeal cavity

Answer 23

ventrally, anterior to foregut, cranial to septum transversum

dorsal to foregut, dorsal to septum transversum,

where IE and EE coeloms are continuous

Question 24

What is the purpose of the dorsal mesentery?

Answer 24

suspends the caudal foregut, midgut and hungut in the peritoneal cavity

Question 25

The septum transversum is the primordium of what?

Answer 25

the central tendon of the diaphragm

Question 26

Describe the formation of the pleuropericardial membranes

Answer 26

pleuropericardial folds located superior to developing lungs enlarge and form pleuropericardial membranes that project into the perocardioperitoneal canals membranes fuse with mesenchyme ventral to esophagus (wk7) pericardial cavity and pleueal cavities are separated

Question 27

Describe the development of the pleuroperitoneal membranes

Answer 27

folds enlarge, project into canals and form membranes as the lungs develop and attach dorsolaterally to the abdominal wall fuse with dorsal mesentary of esophagus and septum transversum myoblasts migrate into the pleuroperitoneal membranes and completes clusure process pleural cavities now separate

Question 28

Describe the development of the diaphragm

Answer 28

septum transversum expands and fuses with dorsla mesentery of teh esophagus and pleuroperitoneal membranes to form central tendon pleuropertoneal membranes fuse with dorsal mesentery of the esophagus and septum transversum to form primordial diaphragm dorsal mesentery becomes median portion of diaphragm myoblasts grow into the dorsal mesentery to form the crura of the diaphram

Question 29

Congenital diaphragmatic hernia

Answer 29

viscera bulge into the pleural cavity lung maturation may be delayed possibly polyhydramnios left side more commonly affected correct in utero/at birth