Visualization of M. tuberculosis in Animal Models Figure 2. Intra-and extracellular M. tuberculosis bacilli in lungs throughout infection from M. tuberculosis infected GKO mice and after 9 days of INH drug treatment. (AR) auramine-rhodamine, hematoxylin QS and DAPI; (H&E) hematoxylin and eosin. (A) An inflammatory lesion from lungs of an M. tuberculosis 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, 1006 magnification). (B) Fluorescent image of an inflammatory lesion from lungs of an M. tuberculosis 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, 2006 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, 4006 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 M. tuberculosis 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, 406 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, 4006 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, 10006 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, 10006 magnification). (I) Fluorescent image of an inflammatory lesion from lungs of an M. tuberculosis infected GKO mouse 28 days after aerosol infection showing intracellular AR+ stained bacilli within multiple macrophages dispersed in non-granulomatous tissue (AR, 2006magnification). (J) AR+ bacilli within a remaining inflammatory lesion from lungs of an M. tuberculosis infected GKO mouse after 10 days of INH treatment (AR, 1006 magnification). (K) PLoS ONE | www.plosone.org 4 March 2011 | Volume 6 | Issue 3 | e17550