Normal Structures and Common Artifacts

A general knowledge of normal lung structure (Figs. 1.1, 1.2, 1.3, 1.4 and 1.5) and common artifacts (Figs. 1.6, 1.7, 1.8 and 1.9) is critical for interpreting lung biopsies. Histologically, there two major types of epithelium within the lungs: respiratory (bronchial/bronchiolar) and alveolar epithelium. The respiratory epithelium lines the proximal and distal airways that start with the trachea, followed by bronchi and variable generations of terminal and respiratory bronchioles. The major histologic difference between a bronchus and a bronchiole is the presence of airway cartilage and submucosal seromucous glands in the former.