Occupational asthma

Bronchial biopsy of a patient with occupational asthma after removal from exposure, showing partial desquamation of the epithelium, thickened basement membrane, and some cellular infiltration.

Low-power photomicrograph of normal lung tissue shows open alveoli with thin, capillary-containing interstitial spaces. An artery (A) is identifiable by its thick, muscular wall; the accompanying bronchus (B) contains mucoid material and is lined by columnar respiratory epithelial cells.