Nkx3.2-Cre drives gene expression in the embryonic pancreatic mesenchyme.

(A) e9.5 Nkx3.2-Cre;R26-YFP^flox/+ embryos were stained with antibodies against YFP (green), Pdx1 (red), and E-Cadherin (blue). YFP positive cells surround both the dorsal and ventral pancreatic epithelia and do not co-stain with the epithelial markers Pdx1 and E-Cadherin. Insert shows higher magnification of E-Cadherin⁺Pdx1⁺ and YFP⁺ cells (B,C,C′) Nkx3.2-Cre;R26-LacZ^f/+ embryos stained with X-gal (blue) and counterstained with Fast Red (pink). (B) LacZ positive cells were found in the mesenchymal but not in the epithelial layer of the e11.5 pancreatic bud (B) and p0 pancreatic tissue (C, C′). (C′) A higher magnification of the areas marked with a box in (C). (D) p0 pancreatic tissues of Nkx3.2-Cre;R26-YFP^f/+ stained for YFP (green) and E-Cadherin (red) to reveal clear separation between Nkx3.2/YFP⁺ cells and E-Cadherin⁺ epithelial cells. (E) Bar diagram shows the mesenchyme area as a percentage of total pancreatic area at the indicated days. Nkx3.2-Cre;R26-LacZ^f/+ e11.5 pancreatic dorsal buds were stained as described in (B) and Nkx3.2-Cre;R26-YFP^f/+ e15.5 and e18.5 pancreata were stained for YFP. The portion of Nkx3.2/YFP and Nkx3.2/LacZ areas were then measured as described in the Materials and Methods. n = 3. M, mesenchyme; E, endodermal epithelium; #, islet of Langerhans; *, duct; V, blood vessel. p values: **p<0.01, ***p<0.005.