Fig. 3. Collagenase exposure altered dextran fluorescein penetration and type 1 collagen morphology indicative of increased barrier permeability. A) Tissue exposed to media containing no collagenase had minimal dextran fluorescein penetration into the mucosa. B) Tissue exposed to low levels of collagenase had increased dextran fluorescein penetration into the mucosa. C) Tissue exposed to high levels of collagenase had increased dextran fluorescein into the mucosa and into the submucosa. D) Average fluorescence intensity of 10 kDa dextran fluorescein penetration into the first 140 μm of the tissue moving from luminal edge towards serosa across treatment groups. E) Type 1 collagen immunoreactivity (COL1-IR) showed distinct vertical crimping pattern with no tortuosity in media with no collagenase. F) Exposure to low levels of collagenase exhibited some COL1-IR tortuosity. G) Exposure to high levels of collagenase increased COL1-IR tortuosity and decreased vertical crimping. Arrows indicate tortuous COL1. H) Tissue not exposed to collagenase exhibits clear claudin-1 immunoreactivity around epithelial cells indicating maintenance of tight junctions. I) Exposure to low levels of collagenase moderately decreased claudin-1 immunoreactivity. J) Exposure to high levels of collagenase dramatically decreased claudin-1 immunoreactivity. L = lumen, m = mucosa, sm = submucosa, cr = crypt, me = muscularis externa, scale bars are 50 μm.