CP Respiratory System Embryology

Question 1

What pharyngeal arch develops into the lungs?

Answer 1

Sixth pharyngeal arch

Question 2

What layer gives rise to the cartilage, smooth muscle, and connective tissue of the respiratory system?

Answer 2

Splanchnic mesoderm

Question 3

In what week is the laryngotracheal diverticulum forming?

Answer 3

4th week

Question 4

During what week do the tracheoesophageal septa close, forming the trachea and esophagus?

Answer 4

5th week

Question 5

What embryological structure gives rise to the laryngeal cartilage?

Answer 5

Neural crest cells

Question 6

What swellings of neural crest cells become the laryngeal cartilages?

Answer 6

Arytenoid swellings

Question 7

In what week does recanalization complete?

Answer 7

By the 10th week

Question 8

What eminence gives rise to the epiglottis?

Answer 8

Hypobranchial / Hypopharyngial eminence

Question 9

What defect is caused by a failure of recanalization?

Answer 9

Laryngeal atresia

Question 10

What are 85% of cases of tracheoesophageal fistulae associated with?

Answer 10

Esophageal atresia

Question 11

In what stage of lung development do we start to see respiratory bronchiole?

Answer 11

Canalicular Stage

Question 12

What weeks make up the canallicular stage?

Answer 12

Week 16 - 25

Question 13

What weeks make up the terminal sac stage?

Answer 13

24 weeks to Birth

Question 14

What weeks make up the alveolar stage

Answer 14

32 weeks to 8 years

Question 15

When do we see surfactant being produced?

Answer 15

Terminal stage

Question 16

What issue makes pulmonary hypoplasia significantly more likely?

Answer 16

Oligohydramnios before 26 weeks

Question 17

What are the steps to make the tracheoesophageal septum?

Answer 17

foregut endoderm from PA 6 becomes the laryngotracheal groove

the groove becomes the laryngeotracheal diverticulum

the diverticulum becomes the tracheoesophageal folds

the folds become the tracheoesophageal septum

Question 18

What forms the glottis?

Answer 18

bilateral arytenoid swellings made from

endoderm covering neural crest cells

Question 19

The hypopharyngeal eminence comes from the

Answer 19

foregut endoderm from PA 3 and 4

Question 20

describe proliferation and recanalization of the larynx

Answer 20

endodermal proliferation closes off the glottis

recanalization (apoptosis re-opening the larynx) occurs by week 10

forms vocal and vestibular folds

Question 21

Trachea endoderm forms what?

splanchnic mesoderm of the trachea forms what?

Answer 21

epithelium and glands of the lungs

cartilage, BV, CT

Question 22

What is the pseudoglandular stage?

Answer 22

wk 5-17

terminal bronchioles and capillaries formed but no interaction

no survival

Question 23

What is the canalicular stage

Answer 23

wk 16-25

respiratory bronchioles and primitive alveoli present

+/- survival, more optimistic towards the 25wk mark

Question 24

What is the saccular stage?

Answer 24

wk 24-birth

type 1 and 2 pneumocytes form

surfactant produced

survival much higher

Question 25

What is the alveolar stage?

Answer 25

wk 32-8yrs old

mature alveoli

susceptible to lung damage (ex. secondhand smoke)

Question 26

What are fetal breathing movements and how are they related to oligohydramnios?

Answer 26

FBM: priming lungs for respiration outside of womb. AKA practice breathing

inhale amniotic fluid, helps form thoracic space and recycles amniotic fluid

oligohydramnios (too little fluid) can lead to pulmonary hypoplasia (lungs weren’t able to form well because they couldn’t perform FBM)

more likely with oligo before 26wks

Question 27

What is Laryngeal Atresia?

Answer 27

failure of recanalization

associated with CHAOS syndrome

dilated airways, lungs enlarged and fluid filled, diaphragm flat/inverted, ascites and/or hydrops

tx: endoscopic dilation of laryngeal web

Question 28

What is the cause of tracheoesophageal fistulae?

What are the s/s?

Answer 28

failure of foregut to proliferated rapidly enough in relation to the rest of the embryo

unable to swallow, lots of drooling, regurgitation, may have reflux into trachea and lungs via fistula

associated with polyhydramnios (too much fluid) because it cannot be swallowed effectively by fetus

Question 29

Pulmonary agenesis

Answer 29

unilateral-absence of a lung or lobe

bilateral=nonviable fetus

Question 30

What is Potter’s Sequence

Answer 30

caused by severe oligohydramnios, resulting in stillborn baby with limb hypoplasia, Potter’s facies, nasal flaring, wide bridge, renal failure

can be associated with renal agenesis

Question 31

Respiratory Distress Syndrome

Answer 31

rapid, labored breathing, seen rarely, but often cause of death in premature infants

deficient surfactant is typically the cause

glassy membrane on xray of lungs

s/s tachypnea, retractions, cyanosis

Question 32

Congenital Lung Cysts

Answer 32

filled with fluid/air

thought to be formed by dilation of terminal bronchi later in fetal life

s/s wheezing, cyanosis, diff. breathing

Question 33

Describe lung development

Answer 33

• laryngotracheal diverticulum forms respiratory bud (4th wk)
• bud forms 1’ bronchial buds that grow laterally into pericardioperitoneal canals
• 1’ bronchial buds branch to form 2’ bronchial buds which form 3’ bronchial buds
• bronchopulmonary segments form in 7th week

(segmental bronchi + mesenchyme)

• pattern is regulated by splanchnic mesoderm

Question 34

Congenital Diaphragmatic Hernia

Answer 34

Bowel can push up thru diaphragm and lead to pulmonary hypoplasia

caused by failure of the pleuroperitoneal membrane to form