An ultrastructural study of bronchiolar lesions in rats induced by 4-ipomeanol, a product from mold-damaged sweet potatoes.

Repeated intraperitoneal injections of 4-ipomeanol in rats resulted in extensive degeneration and necrosis of nonciliated (Clara) bronchiolar epithelial cells. Subsequently there was necrosis and detachment of ciliated cells from the bronchiolar basal lamina. The remaining nonciliated cells divided and differentiated into ciliated epithelial cells and mature Clara cells. The ability of Clara cells to metabolize certain xenobiotics suggests that they may play an important role in the pathogenesis of pulmonary disease and neoplasia.