Application of NBD-PZ to the mucosa of TNBS-induced colitis. (A) Stereomicroscopic observation of the mucosa of TNBS-induced colitis. Bar, 200 μm. (B and C) Fluorescence stereomicroscopic observation of the mucosa of TNBS-induced colitis in PBS only (B) and in PBS containing 1 μg/ml NBD-PZ after incubation at 37°C for three minutes (C). (D) A magnified image of the indicated area in (C). We observed five samples and obtained similar findings. (E) HE stain of the colonic mucosa corresponding to (D). Bar, 200 μm. (F) Immunohistochemical stain of lysosomes using a section adjacent to the section shown in (E).