Embryology 3

Question 1

What part of the embryo does the respiratory system derive from?

Answer 1

Foregut part of the primitive tube

Question 2

What separates primitive oesophagus and trachea as an embryo?

Answer 2

Oesophagotracheal septum

Lung buds enlarge to form lungs

Question 3

If the oesophagus and trachea don’t separate correctly as an embryo, what can this cause?

Answer 3

Trachoesophageal fistula

Oesophageal atresia

Question 4

What part of the embryo does the visceral pleura derive from?

Answer 4

Splanchnic layer of the lateral plate mesoderm

Question 5

What part of the embryo does the parietal pleura derive from?

Answer 5

Somatic layer of the lateral plate mesoderm

Question 6

In embryology, what is formed prior to the formation of the pleural cavity?

Answer 6

Pericardioperitoneal cavity

Question 7

How is the pleural cavity formed?

Answer 7

The pleuro-pericardial fold closes off the pleural cavity from the heart

Question 8

At what stage of the development of the respiratory system does gas exchange begin to occur?

Answer 8

Saccular stage (27- 40 weeks)

Question 9

What is neonatal respiratory distress syndrome?

Answer 9

Caused by surfactant deficiency

Partial collapse of alveoli

Debris consisting of blood elements accumulate - glassy ( hyaline) membrane appearance

Affects 2% of neonates

Makes up 30% of neonatal disease

Question 10

What is lung agenesis?

Answer 10

Failure of lung bud to develop/branch

insufficient mesoderm

Teratogens

Question 11

What is pulmonary hypoplasia?

Answer 11

Abnormally low number/size of bronchopulmonary segments/ alveoli

Question 12

What part of the embryo forms the central tendon of the diaphragm?

Answer 12

Septum transversum - It arises from cranial mesoderm and migrates downwards.

Question 13

What part of the embryo forms the muscular part of the diaphragm?

Answer 13

Skeletal muscle - Grows in from body wall to cover the pleuroperitoneal folds.

Question 14

What part of the embryo forms the left and right diaphragmatic crura?

Answer 14

Dorsal mesentery of oesophagus - Attaches embryonic oesophagus to posterior thoracic wall.

Skeletal muscle ingrowth from body wall then covers dorsal mesentery on each side.

Question 15

How many mesoderm structures create the diaphragm?

Answer 15

4

Question 16

When is the alveolar stage of development?

Answer 16

32 weeks - 8 years

Question 17

What does folding of embryo give rise to?

Answer 17

Primitive gut tube formed from endoderm foregut, midgut, hundgut.

Question 18

What does foregut endoderm give rise to?

Answer 18

Lung bud

Question 19

What does lung bud give rise to?

Answer 19

Trachea and lungs

Question 20

What does pleura arise from?

Answer 20

Lateral plate mesoderm surrounding the lung bud.

Question 21

At 4 weeks where does the trachea and lung bud arise from?

Answer 21

From anterior wall of primitive foregut (endoderm)

Question 22

Where does the trachea lie?

Answer 22

It lies anterior to oesophagus

Question 23

What does a fistula mean?

Answer 23

An abnormal passage between 2 epithelialized tubes or surfaces. TOF is a common congenital abnormality

Question 24

What does atresia mean?

Answer 24

A condition in which an orifice or passage in the body is closed or absent.

Question 25

What is the pericardioperitoneal canal?

Answer 25

It is the space between splanchnic and somatic mesoderm around lungs is initially continuous with both the pericardial cavity anteriorly and peritoneal cavity/abdomen inferiorly. The continuity is called that.

Question 26

What is done to maintain the correct pleural cavity negative air pressure?

Answer 26

The canal needs to be sealed off from the pericardial and peritoneal cavities to become a close spaced around the lungs.

Once it is sealed off, the canal then becomes the definitive pleural cavity

Question 27

What does the plueropericardial folds do to seal off the pleural cavities from the pericardial cavity?

Answer 27

It grows in from the thoracic wall, these folds also form the pericardium around the heart.

Question 28

What happens if the pleuropericardial folds fail to develop?

Answer 28

Pleuropericardial fistula/effusion

Question 29

What is hernia?

Answer 29

Protrusion of an organ through structure or muscle that contains it

It occurs at oesophageal hiatus and sites where structures fail to develop or fuse.

Question 30

Where does primitive gut tube form from?

Answer 30

Endoderm

Question 31

Where does trachea and lungs form from?

Answer 31

Foregut endoderm

Question 32

Where does visceral pleura form from?

Answer 32

Splanchnic (inner) layer of lateral plate mesoderm.

Question 33

Where does parietal pleura form from?

Answer 33

Somatic (outer) layer of lateral plate mesoderm

Question 34

Where does diaphragm form from?

Answer 34

Mainly from cranial and paraxial mesoderm.