1. Volume 117, Issue 6, Pages 1416-1426 (December 1999)
Expansion of Pdx1-expressing pancreatic epithelium and islet neogenesis in transgenic mice overexpressing transforming growth factor α 
Si Young Song*, Maureen Gannon‡, M.K. Washington§, Charles R. Scoggins*, Ingrid M. Meszoely*, James R. Goldenring∥, Christopher R. Marino¶, Eric P. Sandgren#, Robert J. Coffey, Christopher V.E. Wright‡, Steven D. Leach*,‡ 
Gastroenterology 
Volume 117, Issue 6, Pages (December 1999)
DOI: /S (99)
Copyright © 1999 American Gastroenterological Association Terms and Conditions

2. Fig. 1
Serial development of pancreatic pseudoductular metaplasia and early hyperplasia in MT-TGFα mice. (A) Normal histological appearance of nontransgenic mouse pancreas, showing a preponderance of acinar cells with scattered islet tissue (*). (B) Representative section from pancreas of an MT-TGFα mouse 4 weeks after weaning and induction of TGF-α overexpression by zinc supplementation. Intralobular fibrosis is apparent within individual pancreatic lobule (bracket). (C) MT-TGFα pancreas 16 weeks after induction of TGF-α overexpression. Note progression of intralobular and interlobular fibrosis, loss of acinar cell mass, and early appearance of metaplastic tubular complexes (*). (D) Extensive ductal metaplasia in MT-TGFα pancreas 24 weeks after induction of TGF-α overexpression. Loss of acinar cell mass is complete. (E–F) Low-frequency transition to papillary hyperplasia in MT-TGFα pancreas 52 weeks after induction of TGF-α overexpression (arrows). (G–H) TGF-α immunoreactivity in nontransgenic and MT-TGFα transgenic pancreas after 24 weeks of zinc supplementation. (G) Nontransgenic control with no detectable TGF-α immunoreactivity (bracket indicates islet tissue). (H) MT-TGFα transgenic pancreas showing strong expression of TGF-α in metaplastic ductal epithelium. Note negative staining in adjacent islet tissue (bracket). (Original magnifications: A–D, 100×; E, G, and H, 400×; F, 1000×; counterstaining: A–F, H&E; G–H, hematoxylin alone.)
Gastroenterology  , DOI: ( /S (99) )
Copyright © 1999 American Gastroenterological Association Terms and Conditions

3. Fig. 2
Genotyping of Pdx1lacZ/+ and Pdx1lacZ/+/MT-TGFα bitransgenic littermates. F1 progeny from a Pdx1lacZ/+/MT-TGFα cross were genotyped for Pdx1 by Southern blotting and for the MT-TGFα transgene by PCR. (A) Genomic Southern blot of EcoRI-digested genomic DNA from 7 different F1 progeny. The 3.0-kilobase (kb) band represents the wild-type endogenous Pdx1 locus, and the 3.8-kb band represents the targeted locus bearing the lacZ insert. Lanes 1 and 5–7, Pdx1lacZ/+ offspring; lanes 2–4, Pdx1+/+ mice. (B) PCR analysis using genomic DNA from the same 7 mice. The 260-bp product indicates the presence of the MT-TGFα transgene.Lanes 5 and 6, Pdx1lacZ/+ mice; lanes 1 and 7, Pdx1lacZ/+/MT-TGFα bitransgenic littermates.
Gastroenterology  , DOI: ( /S (99) )
Copyright © 1999 American Gastroenterological Association Terms and Conditions

4. Fig. 3
Pdx1 gene activation in metaplastic ductal epithelium. Pancreatic tissue from Pdx1lacZ/+ and Pdx1lacZ/+/MT-TGFα bitransgenic littermates harvested after 24 weeks of zinc supplementation and assessed for Pdx1 gene activation after reaction with Xgal substrate and eosin counterstaining. (A–C) Tissue from Pdx1lacZ/+ control mice; (D–F) tissue from Pdx1lacZ/+/MT-TGFα bitransgenic littermates. (A) Strong Pdx1 expression in islet cell nuclei (bracket) with weak acinar cell activity in Pdx1lacZ/+ control. No Pdx1 gene activation is detected in ductal epithelial cells (arrows; original magnification 400×). (B) High-magnification view of Pdx1lacZ/+ ductal epithelium showing absence of lacZ activity (1000×). (C) Single positive cell (arrow) in otherwise negative Pdx1lacZ/+ ductal epithelium, suggesting the presence of rare Pdx1-expressing ductal epithelial cells in normal pancreas (1000×). (D) Pdx1 gene activation in emerging Pdx1lacZ/+/MT-TGFα metaplastic ductal epithelium (1000×). Note apparent transition between weakly positive acinar cells and strongly positive metaplastic ductal epithelium (arrows). (E) Midsize duct from Pdx1lacZ/+/MT-TGFα bitransgenic mouse with near uniform Pdx1 gene activation in metaplastic epithelium. Note few remaining acinar cells (arrow) characterized by columnar shape, abundant eosinophilic cytoplasm, and weak lacZ activity (1000×). (F) Large metaplastic duct showing uniform Pdx1 gene activation within ductal epithelium (200×).
Gastroenterology  , DOI: ( /S (99) )
Copyright © 1999 American Gastroenterological Association Terms and Conditions

5. Fig. 4
Pluripotent differentiation capacity associated with metaplastic ductal epithelium. Pancreatic tissue from MT-TGFα transgenic mice and nontransgenic control littermates was harvested after 16–24 weeks of zinc supplementation and evaluated for expression of ductal and islet markers using immunohistochemistry. (A) CFTR expression is identified in apical region (arrow) of MT-TGFα metaplastic duct cells, confirming ductal differentiation capacity (original magnification 400×). (B) Expression of the nuclear transcription factor Pax6 in nontransgenic pancreas. Pax6 expression is confined to islet tissue, with no detectable expression in normal ductal epithelium (400×). (C) Pax6 expression in MT-TGFα metaplastic ductal epithelium. In addition to normal islet staining, low-frequency Pax6-expressing cells (arrows) are identifiable in metaplastic ductal epithelium (1000×). (D) Glucagon expression in nontransgenic pancreas is observed in the peripheral aspect of islets, with no staining of adjacent normal ductal epithelium (400×). (E) Evaluation of glucagon expression in MT-TGFα pancreatic tissue shows strong immunoreactivity in metaplastic ductal epithelial cells as well as associated islet tissue (IDC; 200×). (F) Higher-magnification view demonstrating glucagon expression in MT-TGFα metaplastic ductal epithelial cells and associated “inverse bud” of islet tissue (400×). (G) Chromogranin A expression in individual MT-TGFα metaplastic ductal epithelial cells (red reaction product; 400×). (H) Insulin expression by islet tissue in association with MT-TGFα metaplastic ductal epithelium (IDC; 200×). (I) Insulin expression in MT-TGFα metaplastic ductal epithelium with associated early bud of islet tissue (1000×).
Gastroenterology  , DOI: ( /S (99) )
Copyright © 1999 American Gastroenterological Association Terms and Conditions

6. Fig. 5
Double immunofluorescent labeling for Pdx1 (red) and insulin (green) in MT-TGFα pancreas 24 weeks after induction of TGF-α overexpression. (A) Pdx1 immunofluorescence indicates high levels of nuclear Pdx1 protein in metaplastic ductal epithelium, including epithelium with (single arrow) and without (*) associated islet tissue. Note high levels of Pdx1 protein also evident in budding islet tissue (double arrow). (B) Corresponding insulin immunofluorescence. Note that Pdx1-positive and insulin-positive cells are confined to budding islet tissue and associated epithelium. Most of the cells within the metaplastic epithelium are Pdx1 positive and insulin negative, similar to the situation observed during embryonic development. (Original magnification 400×.)
Gastroenterology  , DOI: ( /S (99) )
Copyright © 1999 American Gastroenterological Association Terms and Conditions