Figure 1
Respiratory infection with Ft LVS induces apoptosis and secondary necrosis. Perfused lungs from day 3 Ft-infected (103 CFU) C57BL/6 mice were recovered and processed for histological evaluation. Paraformaldehyde-fixed, paraffin-embedded sections were stained with hematoxylin–eosin (H&E) (a) or TUNEL (b). Evidence of apoptosis and necrotic cell debris was mixed with the ground substance in the lung parenchyma. The ×600 panels represent magnifications of the boxed areas seen in the ×400 panels. Bracketed area (b, ×600) represents the TUNEL-positive fragmented nucleic acid released from the dead/damaged cells. Results are representative of six individual mice. (c) By day 6 p.i., necrotizing inflammation is a hallmark pathology of pulmonary tularemia. Note the accumulation of mixed cellular infiltrates (including PMNs, macrophages, and lymphocytes) in alveolar lumen/interstitium and necrotic areas in the lung parenchyma (×100). Inset picture: necrotic (Nec) lung parenchyma and dead/dying cells (arrow) in the vicinity of necrotic areas (×400).
