Respiratory Embryology Flashcards
How does the respiratory system initially form?
Outpocketing of proximal gut tube = respiratory diverticulum
Initially respiratory diverticulum is continuous with the foregut
Tracheoesophageal septum grows between them
Diverticulum bifurcates into bronchi which then give rise to secondary and teritary bronchi
When does the respiratory system start developing?
Week 4
What are the stages of respiratory development?
Initial development
Pseudoglandular stage
Canalicular stage
Terminal sac stage
When does the pseudoglandular stage occur?
Week 8 - week 16
What happens during the pseudoglandular stage?
Ducts develop within each bronchopulmonary segment around a tertiary bronchi
Bronchiolar buds branch off of tertiary bronchi and proliferate
When does the canalicular stage occur?
Week 16 - week 26
What happens in the canalicular stage?
Respiratory bronchioles branch off of terminal bronchioles
When does the terminal sac stage occur?
Week 26 onwards
What happens in the terminal sac stage?
Alveoli develop
What types of cell develop in the alveoli?
Type 1 pneumocytes
Type 2 pneumocytes
What type of cell are type 1 pneumocytes?
Simple squamous
What type of cell are type 2 pneumocytes?
Simple cuboidal
What is the role of type 2 pneumocytes?
Produce surfactant
