Fig. 3. Notch signaling influences midline cell fate. Ventral views of (A-E) wild-type, (F,G,I,J) Dl³/Dl³, (H) Dl³/Dl⁷ and (K-O) sim-Gal4 UAS-Su(H).VP16 stage 14 Drosophila embryos. Cell types are listed at the top of each column, and the gene or protein assayed that identifies each cell type is listed below. Horizontal bars indicate the location of the midline. (F,I) To differentiate (F) Odd⁺ and (I) wor⁺ midline cells from lateral CNS cells, embryos were double-stained with anti-Sim [not shown, but outlined (dashed line) to show location of midline cells]. In Dl mutants, there was an (F-H) increase in MP1, MP3 (H-cell) and mVUM neurons, and an absence of the (I) MNB and (J) MG. (G) Ectopic ple⁺ cells (arrowheads) were present off the midline; double-staining with anti-Sim indicated that these are not midline-derived (not shown). (K-O) sim-Gal4 UAS-Su(H).VP16 embryos showed the opposite phenotype to Dl mutants: (K-M) strong reduction of MP1, MP3 and mVUM neurons, and increases in (N) MNB and (O) MG.