Figure 3.

Internalization of claudin 4 and occludin in enterocytes of stressed pups at 12 hours. Frozen sections of small intestines of pups submitted to the NEC protocol or DF controls were examined for occludin (ocln, green) and claudins (cldn, green) 2, 4, and 7 by immunofluorescence (top row in each group). Boxed regions correspond to higher-magnification images in the insets. Merged images (bottom row in each group) also show β-actin (red) and DAPI nuclear staining (blue). In DF mice, claudin 2, claudin 4, and occludin were present mainly at TJs, and claudin 7 was detected along cellular membranes. In pups stressed for 12 hours, occludin and claudin 4 were found throughout the cytoplasm. Claudin 2 was largely associated with TJs while claudin 7 was found along the cellular membranes as in dam fed controls. n = 3 to 6 per group. Scale bar = 40 μm.