Fig. 6. The photoreceptors and the projection neurons are born simultaneously and Notch activity is required in cycling progenitors. (A-D') Co-labeling of BrdU (red) with either Tg(HuC:GFP) (A,C) or Tg(AANAT2:GFP) (B,D) in 48-hour-old embryos that have been subjected to a 2-hour BrdU-pulse starting at 18 hours (A-B') or 20.5 hours (C-D'). White arrowheads indicate double-labeled cells. (E) Proportion of BrdU+;GFP+ cells over total number of GFP+ cells after a 2-hour pulse of BrdU. Embryos transgenic for Tg(HuC:GFP) or Tg(AANAT2:GFP) were subjected to a pulse of BrdU starting from various stages. The percent of BrdU+ cells was evaluated at 48 hours. (F-H) Average numbers of Islet1+ neurons, Tg(AANAT2:GFP)+ and Tg(HuC:GFP)+ cells in the epiphysis of DMSO and DAPT-treated embryos. The x-axis indicates the stage at which the treatment starts. Anterior is upwards. Scale bars: 16 µm. Error bars represent s.d. ^*P<0.05; ^**P<0.001; ^***P<0.0005 using a t-test.