Fig. 2. Tg737 expression in pancreatic tissue and islet formation in orpk mice. Staining for ß-galactosidase activity in heterozygous Tg737 mice that carry the lacZ gene under control of the endogenous Tg737 promoter reveals broad expression in the pancreas at E15.5 (A). Expression becomes progressively confined to islets and intercalated ducts in newborn (B) and adult animals (C). Insets in B and C show expression in ductal cells (arrows). Acini in A and islets in B are outlined for a better visualization. Islet formation is unaffected in orpk mice (E,F). Islets were stained with antibodies directed against centrally located insulin (green) and marginally located glucagon-producing cells (red). Quantification of islet areas revealed no difference between wild-type and orpk mice at P9 (D). To adjust for differences in body mass, islet area was divided by body weight. (D; blue, wild type, n=5; red, orpk, n=5). Wild-type islet area was adjusted to `1' to facilitate comparison. Errors bars are shown as ±s.e.m.