Fig. 1. Fng expression in a subset of longitudinal glia (LG). (A-C) Dorsal view of the nervous system of a filleted wild-type embryo at stage 16-17. (A) Anti-HRP (green) reveals the brain lobes (asterisks) and the major axon tracts of the VNC. (B) Repo-positive lateral glia (magenta). (C) Overlay of A and B. (D) Three segments of the VNC of a htl-Gal4, UAS-nGFP embryo. Anti-HRP (green) shows the anterior and posterior commissures in each segment, and the two longitudinal connectives over which the LG (anti-GFP, magenta) are positioned. (E) The six most anterior LG in each hemisegment express Pros (magenta), as do a small number of neurons (arrow). (F) Overlay of D and E without anti-HRP. Note that the Pros channel in D has been converted to green in F, clarifying the distinction between the anterior LG, which express Pros (white), and posterior LG, which do not (magenta). (G) Whole-mount fng in situ hybridization of a stage 15 embryo. Transcripts for fng are observed in a two rows of cells at the dorsal surface of the VNC. (H) Fluorescence in situ hybridization for fng (red), showing a single hemisegment with axons (anti-HRP, blue) and the commissures labeled. (I) The six anterior LG coexpress fng mRNA (red) and Repo (green). Anterior is at the top in all panels of all figures. Scale bars: 50 µm in A for A-C; 10 µm in D for D-F. AC, anterior commissure; PC, posterior commissure.