Fig. 3. GSCs in the expanded or ectopic niche are mitotically active and are able to generate differentiated germ cells. The germaria in A-F are labeled for BrdU (green), ß-gal (red) and Hts (blue). A,B,D,E represent a confocal section, whereas C,F are overlayed confocal images. (A) A hh-lacZ/+ germarium showing that two GSCs (broken lines) close to the cap cells (oval) are BrdU-positive after 3 days of BrdU feeding. (B) A hh-lacZ/+ germarium showing that two GSCs (broken lines) close to the cap cells (oval) have lost their BrdU label 3 weeks after BrdU feeding. (C,C') A germarial tip showing that an expanded cap cell cluster (oval) supports nine GSCs (arrowheads), six of which are BrdU-positive (arrows). (D) The tip of a c587-gal4/+; UAS-N^int/+; hh-lacZ/+ germarium after 3 days of BrdU feeding, showing that a cap cell cluster (oval and white arrowhead) near TF support three GSCs (broken lines), two of which are BrdU-positive, and an ectopic cap cell cluster (oval and black arrowhead) supporting two GSCs (broken lines), one of which is BrdU-positive. (E) The tip of a c587-gal4/+; UAS-N^int/+; hh-lacZ/+ germarium showing that GSCs in an expanded cap cell cluster (unbroken outline indicated by a white arrowhead) and an ectopic cap cell cluster (oval and black arrowhead) are BrdU-negative 3 weeks after BrdU feeding. (F) The tip of a c587-gal4/+; UAS-N^int/+; hh-lacZ/+ germarium showing that one (broken line) of six GSCs (arrowheads) in an expanded cap cell cluster (oval) remains BrdU-positive 3 weeks after BrdU feeding. Scale bar: 10 µm.