FIG. 1.

Histopathologic changes in lungs of mice intranasally immunized with TT plus CT. BALB/c mice were intranasally immunized with TT in combination with CT on days 0 and 7. (a) The alveoli of mice, who died after receiving a high dosage of TT (250 μg) and CT (10 μg) for the second immunization, contained large numbers of macrophages and edema (magnification, 360×). Also, thickening of the alveolar walls was evident. (b) In mice receiving one-third of the primary dose for their second inoculation, there was a massive infiltration of cells around the airways and blood vessels (magnification, 36×). The infiltration also involved alveoli surrounding the vessels and airways.