ULTRASTRUCTURAL LUNG PATHOLOGY OF EXPERIMENTAL CHLAMYDIA-PNEUMONIAE PNEUMONITIS IN MICE

The ultrastructural lung pathology of Swiss Webster mice on days 2, 4, 7, 11, 15, and 21 after intranasal inoculation of Chlamydia pneumonia e AR-39 is described. The inflammatory infiltrate was predominantly po lymorphonuclear leukocytes on day 2. By day 7, mononuclear cells were most prominent in the infiltrate. On day 2, chlamydial inclusions were found frequently in the bronchial ciliated epithelial cells and less frequently in the interstitial cells that appeared to be macrophages. Free particles of all developmental forms of the chlamydial microorgan ism were found in the bronchial lumen and alveolar space. These partic les were likely organisms released from infected cells. Inclusions as well as free particles were difficult to find after day 4. These ultra structural observations suggest an immunopathologic basis for the acut e phase of the disease process.