The influence of small intestinal mucus structure on particle transport ex vivo

•A continuous mucus layer exists throughout the small intestine.•A stratified, inner mucus layer exists adjacent to the epithelium.•The net-like mucus sheets covering the villi have a pore size of 211±7nm.•Particles smaller than the pore size (100nm latex beads) freely diffused through the mucus, while larger particles (500nm latex beads) still demonstrated limited diffusion.•Gaps between mucin sheets may exist allowing passage of larger particles, including bacteria through the stratified layer.