FIG. 1.

Interaction of Salmonella with intestinal mucosa. Transmission electron micrographs of non-follicle-associated epithelia from calves infected with either wild-type S. typhimurium ST4/74 (A and B) or with an isogenic invH mutant (C) are shown. (A) Macrophage from the laminae propriae of the absorptive villi with several internalized bacteria 3 h postinfection. (B) Enterocyte with an internalized bacterium. Note the membrane ruffling. (C) Enterocyte with attached bacteria (invH mutant). No ruffling was observed. Bars, 1 μm. Reprinted from reference 248 with permission of the publisher.