Electron micrographs of the CSF cellular sediment (day 14) (A and B) and the meninges (day 21) (C and D) of rabbits infected with BCG mTNF-α (A and C) or control BCG Montreal (v) (B and D). (A) Cellular sediment from the CSF of a rabbit infected with BCG mTNF-α. Mononuclear cells, including enlarged irregular macrophages (M) and lymphocytes (Ly), are observed. Note mycobacteria inside a tight vacuole (arrows) in the cytoplasm of a parasitized macrophage. Magnification ×3,600. (a) Higher magnification of the mycobacteria-containing vacuole. Magnification ×20,000. (B) Cellular sediment from the CSF of a rabbit infected with BCG Montreal (v). Round lymphocytes (Ly) and monocytes (M) are observed. Phagocytosed mycobacteria were not detected in these cells. Magnification ×2,900. (C) The meninges of a rabbit infected with BCG mTNF-α. A portion of a meningeal area containing a capillary vessel (V) is shown, with lymphocytes (Ly) and monocytes (M) in the perivascular space. Note a migrating lymphocyte crossing the endothelial monolayer at the top of the micrograph. Magnification ×2,900. (D) The meninges of a rabbit infected with BCG Montreal (v). A meningeal vessel (V) is shown. In the perivascular space few migrating macrophages (M) are seen. Magnification ×2,200.