Intra-and extracellular <i>M. tuberculosis</i> bacilli in lungs throughout infection from <i>M. tuberculosis</i> infected GKO mice and after 9 days of INH drug treatment.

<p>(AR) auramine-rhodamine, hematoxylin QS and DAPI; (H&E) hematoxylin and eosin. (A) An inflammatory lesion from lungs of an <i>M. tuberculosis</i> infected GKO mouse 18 days after aerosol infection. The inflammatory lesion shows a mix of macrophages and granulocytes arranged in an unorganized manner (H&E, 100× magnification). (B) Fluorescent image of an inflammatory lesion from lungs of an <i>M. tuberculosis</i> infected GKO mouse 18 days after aerosol infection. Intracellular red fluorescent AR+ stained bacilli were predominantly found uniformly distributed throughout inflammatory lesions at this time (AR, 200× magnification). (C) High magnification fluorescent image of the inflammatory lesion in figure 2B. The lesion shows intracellular AR+ bacilli located within various macrophage cells (AR, 400× magnification). (D) Cropped image taken from figure 2C (square) showing multiple AR+ stained bacilli within a single macrophage cell (AR, digital magnification). (E) A necrotic inflammatory lesion from lungs of an <i>M. tuberculosis</i> infected GKO mouse 28 days after aerosol infection. Multiple foci of intense basophilic staining are seen in alveolar spaces as they accumulate cellular necrotic debris (H&E staining, 40× magnification). (F) High magnification of alveolar spaces filled with cellular necrotic debris located within the inflammatory lesion depicted in figure 2E (square) (H&E staining, 400× magnification). (G) High magnification of a non-necrotic area within the inflammatory lesion seen in figure 2E (star) taken from a serial tissue section. Fluorescent image shows a number of intracellular AR+ stained bacilli residing within macrophages (AR, 1000× magnification). (H) High magnification of an alveolar space filled with necrotic debris located within the inflammatory lesion shown in figure 2E (circle) taken from a serial tissue section. Image shows a high number of extracellular AR+ stained bacilli residing among cellular necrotic debris situated in alveolar spaces (AR, 1000× magnification). (I) Fluorescent image of an inflammatory lesion from lungs of an <i>M. tuberculosis</i> infected GKO mouse 28 days after aerosol infection showing intracellular AR+ stained bacilli within multiple macrophages dispersed in non-granulomatous tissue (AR, 200× magnification). (J) AR+ bacilli within a remaining inflammatory lesion from lungs of an <i>M. tuberculosis</i> infected GKO mouse after 10 days of INH treatment (AR, 100× magnification). (K) Higher magnification of the inflammatory lesion seen in figure 2J. The lesion shows that the majority of remaining AR+ stained bacilli are intracellular within macrophages (AR, 200× magnification). (L) High magnification of the inflammatory lesion seen in figure 2K (square). This fluorescent image shows AR+ bacilli were predominantly found within macrophage cells comprising the few remaining inflammatory lesions (AR, 1000× magnification).