Fig. 1. Schematic of stage 6 (A) and 10 (B) follicles. In all figures, follicles are arranged with anterior towards the left. The arrangement and fates of different cells are indicated by the colors of their nuclei: oocyte (dark brown), nurse cells (light brown), central follicle cells (gray), polar cells (red), stalk cells (light blue), outer border cells (green), stretched cells (pink), centripetal cells (dark blue) and posterior terminal cells (black). Although it is thought that the border, stretched and centripetal cells are specified by stage 6, no markers are available to differentiate them until later.