Fig. 1.

Proliferation in endocrine progenitor cells. After 3 h of BrdU labeling at E15.5, pancreases were dissected from Neurog3^eGFP/+ embryos, and immunofluorescence costaining was performed for eGFP (green; A and D), Neurog3 (red; B and D), and BrdU (blue; C and D). Neurog3⁺/BrdU⁺/eGFP^- and Neurog3⁺/BrdU⁺/eGFP⁺ cells are denoted by yellow arrows and white arrowheads, respectively, and quantified in a bar graph (E). Three embryos were analyzed, and data are presented as the mean ± SEM (**P < 0.01) between two cell populations, by two-tailed Student's t test. (F and G) Dissociated cells from E15.5 and E17.5 Neurog3-Timer embryos were stained with the DNA-specific dye Hoechst 33342 and analyzed by flow cytometry (F). The percentage of proliferating cells at S/G₂/M phases at each population is shown in G. At least eight embryos were analyzed from three different litters for each stage, and data are presented as the mean ± SEM. **P < 0.01, E17.5 vs. E15.5, by two-tailed Student's t test.