Respiratory Embryology

Question 1

What happens in the initial stages of development.

Answer 1

• The respiratory system is derived from the primitive gut tube.
• Week 4: an out-pocketing appears at the foregut called the respiratory diverticulum.
• tracheoesophageal septum seperates foregut and diverticulum.
• The diverticulum bifurcates into two buds, which become the left and right primary bronchi.
• The primary bronchi then proliferate to give rise to secondary and tertiary bronchi.

Question 2

what occurs during the pseudoglandular stage (weeks 7-17)

Answer 2

development of lung except respiratory part (no gas exchange)

Question 3

what occurs during the cannalicular stage (weeks 17-27)

Answer 3

Formation of respiratory part.
Alveolar ducts forms and epithelium starts to develop into type I and II pneumocytes (still no gas exchange).

Question 4

what happens during the saccular stage (27-40 weeks)?

Answer 4

Formation of alveolar sacs, primitive alveoli and surfactant (gas exchange begins).

Question 5

which embryonic structure does the diaphragm develop from?

Answer 5

septum transversum

Question 6

the trachea and lungs develop from which portion of the primitive gut tube?

Answer 6

foregut

Question 7

what is the embryological origin of visceral pleura?

Answer 7

splanchnic layer of lateral plate mesoderm

Question 8

what is the embryological origin of parietal pleura?

Answer 8

somatic layer of lateral plate mesoderm

Question 9

what is the embryological origin of the pleural space?

Answer 9

coelomic cavity

Question 10

what is the origin of the lung buds?

Answer 10

foregut endoderm

Question 11

what seals off the pleural cavity from the pericardial cavity?

Answer 11

pleuropericardial folds

Question 12

what happens during the alveolar stage (32 weeks to 8 years)?

Answer 12

proliferation of alveoli from alveolar sacs.
about 95% of adult alveoli formed postnatally

Question 13

what causes neonatal respiratory distress syndrome?

Answer 13

surfactant deficiency
partial collapse of alveoli

Question 14

what closes off the pleural cavities from the peritoneal cavity of the abdomen? EMBRYOLOGY

Answer 14

pleuroperitoneal folds forming the diaphragm

Question 15

the diaphragm develops from which 4 mesodermal structures?

Answer 15

septum transversum
pleuroperitoneal folds
skeletal muscle ingrowth from peripheral body wall
dorsal mesentery of the oesophagus

Question 16

what part of the diaphragm does the septum transversum form?

Answer 16

central tendon

Question 17

what forms the diaphragmatic crura?

Answer 17

dorsal mesentery of the oesophagus