DNAse type II activity positive epithelial cells in the intestine of infected mice of various age. (A–D) Staining for 5′OH DNA strand ends as a sign of DNase type II activity (green) and immunostaining for S. Typhimurium (red, highlighted by white arrowheads) in small intestinal tissue sections of (A) 5-day-old healthy C57BL/6 mice, (B) 1-day-old mice orally infected with S. Typhimurium at day 2 p.i., as well as (C) 6-day-old mice and (D) adult mice infected with S. Typhimurium at day 4 p.i. Representative images are shown. Counterstaining with DAPI (blue). Bar, 20 μm (A and C) and 50 µm (B). (E) Total number of efferosomes was quantified in at least 16 image fields with the size of 312.35 × 250.61 µm (for neonates) or the size of 624.70 × 501.22 µm (for adults) of small intestinal tissue sections from three or four individual S. Typhimurium–infected neonatal and adult animals at day 4 p.i. One-way ANOVA Kruskal–Wallis test with Dunn’s post-test. ****, P < 0.0001; ns, non-significant.