FIG. 3.

Schematic drawing of the pipette inside the mucus and epithelial layer and of the collected sample. The cylindrical samples contained superficial tissue and the overlying mucus. The three layers were as follows: an epithelial mucus layer (the first 25 μm of mucus from the tissue-mucus interface), a luminal mucus layer (the last 25 μm of mucus to the mucus-lumen interface), and a central mucus layer between the two. The insert shows the further subdivision of the epithelial mucus layer into five sublayers of 5 μm each.