Fig. 3. Duct progenitors express Pdx1 in the period between E9.5-E12.5. Tamoxifen is administered at different stages of development and the HPAP expression in 8-week-old double transgenic animals is determined (when TM is administered to 8-week-old animals, the HPAP staining is performed 3 days later). (A,B) Acini and islet staining when TM was injected at E8.5. In B, the duct is stained brown with HRP-conjugated Wisteria floribunda agglutinin. Note that the brown duct is not blue, whereas acinar cells surrounding the duct are HPAP+ and stain blue. (C) HPAP+ cells within ducts (d), islets (i) and acinar structures when TM was injected at E10.5. (D-F) Acini and islet staining when TM was administered at E12.5 (D), 3 weeks (E) or 8 weeks (F) after birth. (a, acini; d, duct, broken green lines; i, islets, broken red lines; blood vessel, broken black lines.) Scale bars: in B, 20 µm; in F, 20 µm for A, C, D, E and F.