FIG. 2.

Histopathology of selected cavitary rabbit tuberculous lesions. Staining of acid-fast bacilli in paraffin-embedded tissue sections of lung cavity specimens. Magnification, ×20. (A) M. bovis Ravenel-infected rabbit showing fibrosis at the edge of the cavity wall. Bacilli were evident solely at the lining of the central cavity. (B) M. tuberculosis H37Rv-infected rabbit displaying a fibrotic wall with bacilli in the liquefied center. (C) M. tuberculosis CDC1551 ΔsigC mutant-infected rabbit with necrotic and fibrotic areas throughout the cavity. Bacilli are visible in all parts of the cavitary lesion.