Embryos express Tg(ptf1a:eGFP) in the pancreatic domain. Expression of pancreatic markers was analyzed by immuno-fluorescence. Scale bars = 20μm. (A–B′) Confocal projections of pancreatic tissue at 36 hpf. (C–H′) Confocal sections of pancreatic tissue at 60 (C–E′) and 84 hpf (F–H′). Dotted lines delineate Tg(ptf1a:eGFP) expressing tissue. (A–B′) Tg(ptf1a:eGFP) expressing cells initially co-express Nkx6.1 and Prox1. (C–D′) By 60 hpf, N kx6.1 (C,C′, arrow s) and Prox1 (D,D′) expression becomes excluded from the Tg(ptf1a:eGFP) expression domain. (E–F′) Co-expression of Tg(ptf1a:eGFP) with the acinar cell marker Elastase (Ela) is detected by 84 hpf. Elastase positive granules are detected on the apical surface of acinar cells (F′, arrow head ), adjacent to Tg(ptf1a:eGFP) negative intra-pancreatic cells (F, arrow s). (G–H′) The duct marker Nkx6.1 (G,G′) and the endocrine marker Isl1 (H,H′) appear to be restricted to Tg(ptf1a:eGFP) negative ductal and islet cells respectively by 84 hpf. Isl1 is also expressed in the pancreatic mesenchyme (H,H′, arrows).