1. Heterogeneity in expression and subcellular localization of claudins 2, 3, 4, and 5 in the rat liver, pancreas, and gut 
Christoph Rahner, Laura L. Mitic, James M. Anderson 
Gastroenterology 
Volume 120, Issue 2, Pages (February 2001)
DOI: /gast
Copyright © 2001 American Gastroenterological Association Terms and Conditions

2. Fig. 1
Demonstration of antibody specificity by immunocompetition with claudin peptides. Coimmunofluorescent localization of claudin 3 (red) and claudin 5 (red) with ZO-1 (green) in the rat duodenum. Staining for claudin 3 in the presence of claudin 1 peptide (CLDN3+P1) does not interfere with the signal, which colocalizes (yellow) with ZO-1 at the tight junctions of both crypt (C) and villous (V) epithelial cells, whereas staining in the presence of claudin 3 peptide (CLDN3+P3) inhibits immunostaining. Likewise, staining with anti–claudin 5 antibodies is inhibited by claudin 5 (CLDN5+P5) but not by claudin 6 peptide (CLDN5+P6). Also note that claudin 5 is expressed in the junctions of the intravillar arterioles (A) but not the venules (VE), whereas ZO-1 is expressed in both. Nuclei are stained with DAPI (blue). Bar = 100 μm.
Gastroenterology  , DOI: ( /gast )
Copyright © 2001 American Gastroenterological Association Terms and Conditions

3. Fig. 2
Immunoblot analysis of claudins 2–5 in rat gastric fundus, pyloric antrum, duodenum, jejunum, ileum, proximal colon, and liver. Protein (100 μg) is loaded from each tissue; approximately equal levels of β-tubulin detected in each confirm equal loading.
Gastroenterology  , DOI: ( /gast )
Copyright © 2001 American Gastroenterological Association Terms and Conditions

4. Fig. 3
Immunolocalization of claudins 2–5 in the rat liver lobule. A conventional H&E-stained section illustrating the acinar orientation of the immunofluorescent images. Claudin 2 is not expressed in the tight junctions of hepatocytes around the portal vein (PV) but increases along the lobule toward the central vein (CV). Claudin 3 is expressed uniformly throughout the lobule, claudin 4 is not detected in the liver, and claudin 5 is only detected in the tight junctions of endothelial cells in the hepatic arteries (HA) and portal vein but not the sinusoidal endothelial cells. Nuclei are stained with DAPI (blue). Bar = 50 μm.
Gastroenterology  , DOI: ( /gast )
Copyright © 2001 American Gastroenterological Association Terms and Conditions

5. Fig. 4
High-magnification double-immunofluorescent localization of claudins 3 and 5 (green) with ZO-1 (red) in rat liver. Claudin 3 colocalizes (yellow) with ZO-1 continuously along paired tight junctions flanking the canalicular margins. ZO-1, but not claudin 3, is expressed in the junctions of sinusoidal endothelial cells (S). Claudin 5 is only expressed in the junctions of endothelial cells in the hepatic arteries (HA) and does not colocalize with ZO-1, which is expressed in junctions of bile duct epithelial cells (BD), and paired junctions flanking the canaliculi (arrows). Nuclei are stained with DAPI (blue). Bar = 10 μm.
Gastroenterology  , DOI: ( /gast )
Copyright © 2001 American Gastroenterological Association Terms and Conditions

6. Fig. 5
Double immunofluorescent localization of claudins 2–5 (red) with occludin (green) in the rat pancreas. Occludin is expressed in the tight junctions of epithelial cells within the acini (A) and ducts (D), with expression highest in the acinar cells. In contrast, claudin 2 is more highly expressed in the ducts, whereas claudins 3 and 4 are more equally expressed in acinar and duct junctions. Claudin 5 is expressed in acinar but not duct junctions (not shown). Claudin 4, but not the other claudins, is expressed in the tight junctions of β cells of the pancreatic islets (PI). The pancreatic islets were recognized by phase contrast microscopy and outlined with dashed white lines. Nuclei are stained with DAPI (blue). Bar = 100 μm.
Gastroenterology  , DOI: ( /gast )
Copyright © 2001 American Gastroenterological Association Terms and Conditions

7. Fig. 6
Immunolocalization of the claudins 2–5 in stomach, jejunum, and proximal colon of the rat. The surface epithelia or villi are oriented upward and the glands or crypts downward. Claudin 2 is not detected in the fundus, and in the small and large intestine shows a decreasing gradient of expression from crypts to the villus surface cells. Claudin 3 is expressed in both glands and surface cells in the stomach on the lateral membrane; in the small and large intestines it is junctional, but in the colon it shows an increasingly lateral localization from the crypts to surface. Claudin 4 is junctional in the gastric glands, lateral in the small intestine, and in the colon highly restricted to a subset of surface cells where it is both junctional and lateral. Claudin 5 is lateral in both glands and surface cells of the stomach, and predominantly junctional along the crypt-to-villus surface axis in the small and large intestine. Bar = 100 μm.
Gastroenterology  , DOI: ( /gast )
Copyright © 2001 American Gastroenterological Association Terms and Conditions