MH 137 Lung Fetal

Lung Fetal

This early stage of lung development is known as the pseudoglandular stage. The lung is not capable of supporting respiration.

• Conducting Pathways
  • Developing Bronchi
    • Pseudostratified Columnar Epithelium with Cilia
    • Bronchial Cartilage - the developing cartilage is initially eosinophilic because of the absence of proteoglycans, but after their addition the mature cartilage is more basophilic.
  • Bronchioles
    • Primary Bronchioles - change from ciliated pseudostratified to simple columnar epithelium with Club cells. (None are present on this slide.)
    • Terminal Bronchioles - changes from ciliated columnar to simple cuboidal epithelium with more Club cells.
    • Respiratory Bronchioles (#1,#2) - lined with simple cuboidal epithelium with Club cells. (Not distinguishable at this stage.)
• Respiratory Regions - compact tissue compared to the adult lung. They are lined with a simple cuboidal epithelium of early type II pneumocytes.
  • Alveolar Ducts - arise from respiratory bronchioles and are passageways lined with a simple cuboidal epithelium and relatively few alveoli.
  • Alveoli - small spherical or duct-like structures.