Fig. 4. dpp directly signals to anterior PGCs at the early pupal stage of ovarian development. All female gonads were isolated from early pupa. (A,B) A wild-type gonad labeled for BrdU (green, nuclei) and Vasa (red, cytoplasm), showing that the PGCs close to TFs/cap cells have a higher tendency to be BrdU-positive than the other PGCs. Several BrdU-positive somatic cells in the germ cell zone are indicated by arrows. (B) Area in A outlined by broken lines, showing anterior BrdU-positive PGCs (arrowheads) and a BrdU-positive somatic cell (arrow). (C,D) A gonad labeled for dpp mRNA (red) and Hts (green), showing the expression of dpp mRNA in anterior somatic cells. (D) Boxed area in C at higher magnification, showing dpp mRNA in TFs and cap cells (arrowhead) but not in PGCs indicated by spectrosomes (arrow). (E,F) A Dad-lacZ/+ gonad labeled for lacZ (red) and Hts (green), showing that Dad is preferentially expressed in the PGCs close to TFs/cap cells. (F) Boxed area in E at higher magnification, showing a Dad-positive PGC (outlined by an unbroken line) adjacent to TFs/cap cells and a Dad-negative PGC lying more posterior (outlined by a broken line). Scale bars: 20 µm for A,C,E.