Virulent <i>S. flexneri</i> cells escape pharyngeal grinding and accumulate in the <i>C. elegans</i> intestinal lumen.

<p><b>A:</b> Schematic representation of the <i>C. elegans</i> body plan with the plane of sections highlighted (artwork by Altun and Hall, © Wormatlas). <b>B:</b> Transverse section of the mid body of a healthy nematode with the intestinal cell highlighted in yellow. <b>C–H:</b> Transmission electron microscopy micrographs of transverse mid body sections of animals feeding on plasmid-cured, avirulent <i>S. flexneri</i> (SFL1223) (<b>C, E, G</b>) and virulent <i>S. flexneri</i> serotype 3b (SFL1520) (<b>D, F, H</b>) for 24 h (<b>C, D</b>), 96 h (<b>E, F</b>) and 144 h (<b>G, H</b>). IEC-intestinal epithelial cell; mv-microvilli; IL-intestinal lumen; b-intact <i>S. flexneri</i> cells.</p>