FIG 5.

Neutrophil homing from blood to Peyer's patches. (A) Absolute number of neutrophils in the blood of mice at day 3 after infection with Y. enterocolitica WT or ΔyopH strains. (B) Relation of absolute number of neutrophils in Peyer's patches (PP) to absolute number of neutrophils in blood of each infected mouse at 3 days postinfection (dpi). (C) Histological analysis of migration of neutrophils. Sections of PP from mice that received PBS (control) and from infected mice at 3 dpi were stained with hematoxylin and eosin. Photographs show blood neutrophils (arrows) and neutrophils in PP (arrowhead) (magnification, ×400; insets, ×1,000). In the infection by the WT strain, the inset shows an amplification of two neutrophils in blood vessels (v). In the ΔyopH strain infection, the inset shows at greater magnification an extravasing neutrophil. Photographs are representative of 1 of 4 mice per group of 2 independent experiments. (D) Quantification of results from multiple independent images (n = 5 per group). The data in panels A and B are the summary results of 2 experiments. Each symbol represents an individual mouse in panels A and B or a single image in panel D; horizontal lines indicate the means (*, P < 0.05; ***, P < 0.001).