Fig. 5.

Model - ectopic Jak/Stat signaling sporadically prevents CySC differentiation. A diagram showing a model for the role of HS in Upd/Stat signal distribution. (A) In wild-type, HS on the hub retains the majority of Upd ligand at the niche. Only CySCs (yellow) and GSCs (single blue cells) that contact the hub receive sufficient Jak/Stat signaling (green) to be renewed as stem cells. (B) When HS is lost, the Upd/Stat signaling range is expanded, resulting in stochastic ectopic renewal of cyst cell daughters as CySCs. This decouples the differentiation of CCs and germline cells, which leads to ectopic populations of stem cells. This figure is available in black and white in print and in color at Glycobiologyonline.