DEVELOPMENTAL STAGE

EMBRYONIC

PSEUDOGLANDULAR

CANALICULAR

TERMINAL SAC

ALVEOLAR

Gestation

0 - 6 weeks

7 - 16 weeks

17 - 24 weeks

25 - 36 weeks

>37 weeks

Structural morphogenesis

Trachea, bronchi

Bronchioles, terminal bronchioles, lung circulation

Respiratory bronchioles, primitive alveoli

Alveolar ducts, thin-walled alveolar sacs, increasing functional type 2 cells^a

Definitive alveoli and mature type 2 cells^a

Disease manifestation

Tracheoesophageal fistula, pulmonary sequestration

Bronchogenic cyst, congenital diaphragmatic hernia, congenital cystic adenomatoid malformation

Pulmonary hypoplasia, RDS, BPD, alveolar capillary dysplasia

RDS, BPD

TIN, MAS, neonatal pneumonia, PPHN