FIG. 5.

Histopathological damage is greater in the spleens and livers of A/J mice than in those of C57BL/6 mice. The A/J and C57BL/6 mice were anesthetized as previously described and then inoculated i.g. with a 0.1 LD₅₀ challenge of L. monocytogenes Scott A (10⁵ and 10⁷ CFU, respectively). The mice were euthanized at 72 h after challenge, and their tissues were transferred to buffered formalin. Following fixation, thin sections of the tissues were cut, mounted on glass slides, and stained with hemotoxylin and eosin. (A) Disruption of a germinal center in spleen tissue of an A/J mouse, with infiltration of neutrophils and macrophages. (B) Normal-appearing spleen tissue from a C57BL/6 mouse. (C) Liver tissue from an A/J mouse exhibiting necrotic foci (arrows) with infiltration of neutrophils and macrophages. Gram-stained sections frequently revealed the presence of intracellular bacteria in these lesions (data not shown). (D) In contrast to the A/J mouse liver tissue, liver tissue from a C57BL/6 mouse appears relatively normal. Magnification, ×180 (original magnification, ×200).