4 stage cross-section of the bronchus demonstrating the tissue changes occurring in asthma and chronic bronchitis. 4-stages are : Normal Bronchus, Hypersecretion of mucous gland, swelling with lymphoid aggregations and smooth- muscle spasm. This model includes: cartilage, mucous glands and plug, spiraling smooth muscles and fibroelastic tissue and epithelial layers of the bronchus. All stages rotate on hinge pin.