15 min. each. Sections were blocked with a mouse-on-mouse Ig blocking reagent (Vector Laboratories, Inc., Burlingame, Califor- nia) for 1 hour at RT. Biotinylated antimouse IgG was pre-labeled with the anti-pimonidazole antibody for 10 min. and was applied to slides overnight at 4uC. Liquid DAB (DAKO, Carpinteria, California) was applied to slides for 5–10 min. to visualize the reaction. Finally, slides were counterstained with Gill’s Hematox- ylin (Sigma Chemical Co., St. Louis, MO) for 10 min. and cover- slipped. Fluorescent and Confocal Microscopy Photographs were taken on a Nikon Eclipse 80i with DAPI, FITC and TRITC filter sets and an Optronics Microfire color fluorescent camera. Multiple photographs were taken under different focal planes when necessary and combined using the Extended Depth of Focus (EDF) function on Nikon NIS Elements AR 3.0 software. Confocal images were captured on a Zeiss LSM References 1. (2003) WHO annual report on global TB control–summary. 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