Prox1 deletion in pancreatic progenitors reduces early pancreas growth. (A) Frozen section of an E11.5 Pdx1-CreEARLY; ROSA26R embryo stained with X-gal validates Cre recombinase activity in pancreatic progenitors. (B) qRT-PCR results at E12.5 (n = 3) show that a reduction in Prox1 expression is accompanied by an increment of amylase expression in Prox1ΔPanc pancreata. (C) Immunohistochemistry results show almost no Prox1 protein expression and reduced branches (arrows) in Prox1ΔPanc pancreata compared with control pancreata at E13.5. (D and E) Immunohistochemistry and morphometric results indicate that Prox1ΔPanc pancreata are smaller (Ecad+ area; D, dotted lines; E [left], n = 3) and have less proliferating cells (PH3+; E [right], n = 3) than control pancreata at E15.5. Scale bars = 50 μm (C), 100 μm (D). *P < .05, ***P < .001.