Fetal Lung Development Canalicular Stage 16 n-24 week Terminal Saccular Stage -24th-36th week Intersaccular septa Squamous epithelium Transitory ducts Artery Terminal buds Myofibroblasts Myofibroblast R Columna epithelium Capillaries Terminal bronchiole Respiratory bronchiole Diated acinar tubules Respiratory bronchiole Transitory saccules 16-24 weeks 24-36 weeks Respiratory bronchioles Transitory saccules and ducts
Fetal Lung Development Canalicular Stage ~ 16th – 24th week Terminal Saccular Stage ~ 24th – 36th week Respiratory bronchioles Transitory saccules and ducts
Postnatal Lung Development Postnatal Development birth-8 year Alveolar period Primary Alveolar Septa Pnmary alveoar septa 3 Alveolar duct Myot:broblasts 'SWE ansitory ducts Terminal bronc Terminal Respiratory bronchiole Respiratory bronchiole Alveoli Capil c 36 weeks D Postnatal Secondary alveolar septa Alveolar ducts and alveoli
Postnatal Lung Development Postnatal Development ~ birth – 8 year Alveolar period Secondary alveolar septa Alveolar ducts and alveoli
Surfactant start synthesis in 20-24w o· docto increase in 28-32w J八∧ meet demands after 35w bodle body Y double in alveolar within 24h Type I ca adult level after 3-7d s- TyPe l Cell √haf-life12~24h Blood v renew in 24-48, >90% reuse Type I Cell
Surfactant ✓start synthesis in 20~24w ✓increase in 28~32w ✓meet demands after 35w ✓double in alveolar within 24h ✓adult level after 3~7d ✓half-life 12~24h ✓renew in 24~48,>90% reuse