Fig. 7. A model for GSC differentiation. Somatic cells of the niche (TF, terminal
filament), cap cells (CpC) and inner sheath cells (IS) are depicted in red.
Germ line cells are depicted in shades of green (GSC, germ line stem cell;
Pre-Cb, pre-cystoblast; Cb, cystoblast). Stem cell maintenance is controlled
by dpp, pum, and other unidentified factors (dashed lines). Zpg is
needed for the differentiation of the stem cell. Bam and Bgcn are needed for
the differentiation of the cystoblast and cysts.