C57BL/6 mice were challenged, by aerosol, with 10-30 CFU Mtb-WT, Mtb-Δeis, or Mtb-c-eis and sacrificed 4 weeks post-infection. (A) High- and low-magnification electron micrographs of lung tissue sections from mice infected with Mtb-Δeis show accumulation of autophagic vesicles (black arrow, bacteria in autophagic vacuoles; white arrow, degradative autophagic vacuoles). Scale bars: 2 µm (left upper), 0.5 µm (right). Numbers of autophagic vacuoles per cell in each TEM section (left lower) (mean±SD; n = 50). 