Title: Respiratory bronchiole
Stain Azan, human. The lumen (1) shows an irregular lining. It is covered by low columnar - cuboidal cells (→). Alveolar pouches (*) within the same lumen are lined by thin alveolar epithelium as found in
the surrounding alveoli (2). At (5) small patch of smooth muscle,
(4) macrophages with phagocytized carbon particles. (2a) indicates area of alveolar duct and (3) a small branched pulmonary artery.
Title: Transition of respiratory bronchiole into alveolar duct in the lung
Stain Azan, human. The alveolar duct (1↔) exhibits an alveolated wall but at few places (3) bronchiolar characteristics are evident such
as cuboidal epithelium covering small areas of smooth muscle and connective tissue. They differ from the characteristic alveolar tips (2↓) of neighbouring thin-walled alveoli (A). The tips (2) contain elastin masked by collagen (blue-stained) and are covered by thin alveolar cells type I.
Keywords/Mesh: respiratory tract, lung, respiratory bronchiole, alveolar duct, columnar epithelium, cuboidal epithelium, alveolar epithelium, alveolus, alveolar tip, smooth muscle, elastin, collagen, phagocytosis, histology, POJA collection