Embryology 2

Question 1

How does the embryo fold to form the gut tube?

Answer 1

amniotic cavity folds down and yolk

Question 2

Where does the lung tube come from?

Answer 2

the gut tube - endoderm

Question 3

Where does the cartilage, connective tissue and muscle derive from?

Answer 3

splanchnic mesoderm

Question 4

What is the name of the outpouching of the foregut and when does it further develop?

Answer 4

respiratory diverticulum on the front. develops into lung buds at week 4

Question 5

What splits the foregut oesophagus and the trachea?

Answer 5

tracheoesophageal ridge

Question 6

What happens at week 5?

Answer 6

bronchial buds form.

Question 7

What happens at week 6?

Answer 7

6 - right bronchi forms 3 secondary bronchi and left forms 2. mesoderm covers the outer lung with pleura (somatic - parietal and splanchnic - visceral)

Question 8

What happens at week 8?

Answer 8

bronchi grows so much that its attached to the pleura. terminal bronchioles with terminal sacs form.

Question 9

How is the pleura formed?

Answer 9

lung bud pushes against the intraembryonic coelom.

Question 10

What splits the pleural and pericardial cavities?

Answer 10

pleuropericardial folds. separates lungs and pericardium by forming a separate pericardial cavity

Question 11

What covers the pericardial cavity?

Answer 11

somatic mesoderm

Question 12

Which weeks are the embryonic stage and what occurs?

Answer 12

weeks 4-7. lung bud appears.

Question 13

What weeks are the pseudoglandular stage and what occurs?

Answer 13

weeks 7-17. lungs develop but no respiratory part

Question 14

What weeks are the canalicular stage and what occurs?

Answer 14

weeks 17-27. respiratory part develops. alveolar ducts form and epithelium differentiates into type I and II pneumocytes

Question 15

What weeks are the saccular stage and what occurs?

Answer 15

weeks 27-40. alveolar sacs form and primitive alveoli and surfactant is made.

Question 16

What is the postnatal period and what occurs?

Answer 16

32 weeks to 8 years. proliferation of alveolar sacs to alveoli.

Question 17

How much of our alveoli is formed postnatally?

Answer 17

95%.

Question 18

How is atresia and a fistula made?

Answer 18

these are congenital abnormalities. trachea and oesophagus don’t separate - fistula. atresia is when the oesophagus isn’t formed and is closed off

Question 19

What is lung agenesis? whats the cause?

Answer 19

failure of a lung bud to develop or branch, causing absence of lung. could be due to insufficient no. of mesoderm cells, or teratogens

Question 20

What is pulmonary hypoplasia?

Answer 20

incomplete development of lungs. leads to abnormally low no. or size of broncho-pulmonary segments - small lungs

Question 21

How many structures form the diaphragm? what are they made from?

Answer 21

4. made from mesoderm.

Question 22

When does diaphragmatic development occur and what is it?

Answer 22

end of 5th week. separates thoracic and abdominal cavity

Question 23

What 4 parts fuse to form the diaphragm?

Answer 23

septum transversarium, pleuroperitoneal fold, oesophagus mesentery and muscular ingrowth from body wall

Question 24

What does the septum transversarium form?

Answer 24

the central tendon of the diaphragm

Question 25

What may lead to a hiatal hernia?

Answer 25

incomplete closing of diaphragm during development. organs may protrude

Question 26

What is a diaphragmatic hernia?

Answer 26

gap in diaphragm. small intestine can enter left chest and push heart and lungs to the right. liver can push into chest, causing pulmonary hypo-plasia (small lungs)

Question 27

What embryological structure forms the superior surface of the diaphragm?

Answer 27

parietal pleura, so somatic lateral plate mesoderm