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Figure 2. Endocrine and Exocrine Cells Are Both Present in Ectopic Pancreas(A–F) Expression of endocrine genes. (A–C) Insulin RNA expression; (D–F) glucagon RNA expression. (A) Wild-type insulin expression. Expression is only seen in the dorsal pancreas (black arrow) at this stage in several prominent clusters. The liver (L) is located on the opposite side of the duodenum (red arrowhead). The two dark spots on the stomach are melanocytes and not insulin-stained cells. (B) TTR-Xlhbox8-VP16 transgenic whole gut. Several ectopic clusters of insulin expression are seen in the ectopic pancreatic tissue (EP) opposite the pancreas (outlined in white). (C) Section of (B) showing the ectopic pancreas (EP, dotted line) opposite the endogenous pancreas (solid line) with two clusters of insulin-expressing cells. (D) Wild-type glucagon expression. Expression is seen in several spots within the pancreas. (E) TTR-Xlhbox8-VP16 transgenic gut. Ectopic glucagon expression is found in the position of the liver (EP, outlined in white) opposite the normal pancreas. Note that glucagon cells are normally found in stomach and intestine, as well as pancreas, but not in the liver [37–39]. (F) Section of (E) showing glucagon expression within the ectopic pancreas (dotted line).(G–I) Ectopic expression of exocrine markers in the liver of transgenic tadpoles. (G) Live image of a TTR-Xlhbox8-VP16:Elas-GFP transgenic tadpole, showing ectopic elastase-GFP fluorescence within the liver (red arrowhead), anterior to the normal pancreas (P). (H) Amylase RNA expression. Ectopic expression of amylase is seen in the position of the liver (EP) as well as in the normal pancreas (P), in an identical pattern to the Elas-GFP. (I) Section of (H) showing expression of amylase in a portion of the liver (L), as highlighted by the dotted line. Normal amylase RNA expression is seen throughout the pancreas (solid black line). L, liver; P, normal pancreas; EP, ectopic pancreas. |
