The picture of leukocyte infiltration of the lung tissue of I/St (left) and B6 (right) mice infected with 2×10³ CFU of <i>M. avium</i> via aerosol route 8 weeks earlier.

<p>Peroxidase immune staining with hematoxylin counter-staining (×150). Cell populations are indicated on the left side. See text for the description.