ZOO 3713C Lecture Notes - Lecture 15: Bronchus, Bronchiole, Alveolar Cells
Document Summary
Tubular branching system controlled by inductive interactions between the mesoderm and the endoderm. Adult anatomy: trachea, primary bronchi, secondary bronchi, tertiary bronchi, bronchiole, terminal bronchiole, alveolar duct, alveolar sac. Until week 7 formation of the trachea and bronchial tree. 1st branching lung bud comes off ventrally form the foregut: called respiratory diverticulum. 2nd branching bifurcation to left and right primary bronchial buds trachea and larynx is formed. 3rd branching asymmetric right and left primary bronchi: right side 3 secondary bronchial buds, left side 2 secondary bronchial buds, buds are primordia for lung lobes. 4th branching: right- 10 tertiary bronchi, left 8 tertiary bronchi. 14 more branching to form the respiratory tree- producing terminal bronchioles. Terminal bronchiole divides into 2 or more respiratory bronchioles. Completion of this period is required for survival of premature infants. Final branching of respiratory bronchioles associated with dense network of capillaries terminal sacs or primitive alveoli.
