Irritant-induced asthma

Bronchial biopsy taken two years after an acute accidental inhalation of chlorine showing severe desquamation of epithelial cells. Smooth muscle cells are surrounded by reticulocollagenic fibrous tissue seen in the center part of the figure. Weigert-Masson trichrome stain.

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.