Body Folding & Body Cavities

Question 1

Where does the intraembryonic coelom form?

Answer 1

in the middle of the lateral plate mesoderm

Question 2

What does the intraembryonic coelom split the lateral plate mesoderm into?

Answer 2

somatic lateral plate mesoderm

splanchnic lateral plate mesoderm

Question 3

What are the three components of the intraembryonic coelom?

Answer 3

• pericardial cavity
• pleural cavities (pericardioperitoneal canals)
• peritoneal cavity

Question 4

What is the extraembryonic coelom?

Answer 4

-cavity filled with amniotic fluid

Question 5

What germ layers line the extraembryonic coelom?

Answer 5

• ectoderm

- extraembryonic mesoderm

Question 6

What is the intraembryonic coelom?

Answer 6

horseshoe-shaped fluid-filled space that becomes the three main body cavities

Question 7

What germ layer lines the intraembryonic coelom?

Answer 7

lateral plate mesoderm

Question 8

The somatic lateral plate mesoderm is next to which other germ layer?

Answer 8

ectoderm

Question 9

The splanchnic lateral plate mesoderm is next to which other germ layer?

Answer 9

endoderm

Question 10

Which folds develop to separate the intraembryonic coelom into its three components?

Answer 10

• pleuropericardial folds
• pleuroperitoneal folds

become pleuropericardial and pleuroperitoneal membranes

Question 11

What germ layer forms the pleuropericardial folds?

Answer 11

somatic mesoderm

Question 12

What four components form the thoracic diaphragm?

Answer 12

• septum transversum
• pleuroperitoneal membranes
• dorsal mesentary
• myoblasts

Question 13

Pathology: Gastroschisis

Answer 13

• 1/3,000 live births
• protrusion of viscera (R of the umbilical cord)
• bowel uncovered, floating in amniotic fluid
• more common in thin Caucasian mothers younger than 20 yrs

Question 14

Pathology: Congenital Epigastric Hernia

Answer 14

• midline bulge of abdominal wall b/w xiphoid process and umbilicus
• bowel not exposed, covered by skin and subcutaneous tissue

Question 15

What is the embryological cause of gastroschisis and congenital epigastric hernia?

Answer 15

• failure of lateral body folds to fuse completely when the anterior abdominal wall forms
• during week 4

Question 16

Pathology: Congenital Diaphragmatic Hernia

Answer 16

• 1/2,200 live births
• viscera bulge into pleural cavity
• cause delayed lung maturation
• polyhydramnios may be present
• 80% occur on the L side because the L canal is larger

Question 17

What is the embryological cause of a congenital diaphragmatic hernia?

Answer 17

-lack of myoblast infiltration leaves the left pericardioperitoneal canal open