ABSTRACT
In the present investigation, the morphological and ultrastructural alterations in both trachea and lung of rat following nicotine treatment were studied using scanning and transmission electron microscopy. Adult male albino rats, injected subcutaneously with a high dose of nicotine [25 mg/kg body weight] for 15 successive days, were used in the present study. Nicotine induced extensive morphological and ultrastructural changes in both trachea and lung tissues. The respiratory epithelium of trachea changed to stratified squamous form with a remarkable increase in goblet cells. Moreover, the loss and destruction of cilia in most of the ciliated columnar epithelium and the increase of brush cells in nicotine treated rat mucosa were also detected. Marked thickening of the interalveolar septa, lymphatic infiltration and degenerated cells were observed in lung tissue. Type II pneumocytes with an increase in surfactant bodies, necrotic cells, cell debris and macrophages, together with a marked increase in the thickness of collagen fibers were revealed in the lung tissue. Furthermore, necrotic cells with degenerated cellular organelles were observed in both trachea and lung tissue. In conclusion, nicotine is considered as a toxicant with a unique progression of injury