Lung Embryology
Sat, 08/15/2009 - 03:43 — saif
Lung Embryology
- LRT (lower respiratory tract) arises from laryngotracheal diverticulum.
- Wk 24 – resp bronchi form, respiration is possible
- Wk 29 – type II secrete surfactant (reaches adequate levels 2 wks before birth)
- Trachea – C-shaped cartilage
- Left bronchus longer, narrower, greater angle; bronchi have circum rings of crtlg; pseudostrat colum epi, Goblet, neuosecr, basal, brush cells
- Epi à lamina propria à submuc à cartilage
- Bronchioles – no cartilage, submucosal glands
1) membranous – smooth muscle wall; ciliated columnar cells + Clara cells
2) respiratory – alveolar ducts, alveoli budding from wals; no musc. wall; cuboidal cells +/- cilia