(A–D and I) Stage 17 gonads, merge of Vasa (red, germ cells), Hoechst (blue, DNA), and Fas3 (white, niche cells), or single channel (Fas3); dotted line, gonad boundary. Scale bars, 10 μm. Prime panels show Fas3 (niche cells, arrowheads) alone.
(A) Sibling controls have a single, anterior niche.
(B and C) Df(2R)BSC25 gonads, with a deletion removing pyr and ths genes, exhibit niche defects such as (B) dispersed niche cell aggregates and (C) niches not at the gonad anterior (asterisk, gonad posterior).
(D) slit[2] mutant gonads often have dispersed niche cell aggregates.
(E–H) Quantification of niche defects (Fisher’s exact test), (E) with pyr and ths removed (fgf) (p = 0.016), (F) FGF htl receptor mutant (p = 0.0003), (G) slit mutant (p < 0.0001), and (H) robo2, robo1 double mutant (p = 0.024).
(I and J) Combined mutant with slit, and pyr and ths removed (fgf) exhibit dispersed niche cells (p = 0.003).
(K) Niche morphogenesis defects were not significant (n.s.) in Slit overexpression embryos.