ASTHMA, DRAWING. ASTHMA, DRAWING Asthmatic bronchus. Illustration of a bronchus during an asthma attack. From the outside inwards: the muscle layer is hypertrophic, immune cells (mastocytes, lymphocytes, eosinophilic leukocytes) are present in the inflamed bronchial mucosa and there is excessive mucus secretion with desquamation of the epithelial cells. The combination of these factors has narrowed the bronchial lumen, blocking the passage of air.