Experimental type 25 pneumococcal pneumonia in rats: an electron-microscopic study.

A self-healing lobar pneumonia was produced in rats by intratracheal instillation of Type 25 pneumococci. Sequential changes in the lung were examined by electron microscopy from the onset of acute inflammation through resolution. Manifestations of the infection included vascular endothelial changes of acute inflammation and leukocytic mobilization. The pulmonary alveolar epithelium showed only minimal changes throughout the infection. The significance of the findings is discussed in relation to the pathogenesis of pneumococcal lobar pneumonia.