Fig. 7. dri expression in the longitudinal glial cells of the Drosophila embryonic CNS depends on GCM and REPO. Dorsal view of dissected embryonic ventral nerve cords immunochemically stained with anti-DRI and detected with AP-conjugated secondary antibody. Anterior is towards the left. (A) The distribution of dri-expressing cells in wild-type embryos. (B) dri expression is completely abolished in all glial (arrow) but not neural (arrowhead) cells in the gcmP1 mutants. (C) dri expression is lost from most longitudinal glial cells but not from the neurone (arrowhead) nor, perhaps, from A/B SPG (thin arrows) in a repo³ mutant embryo. (D) Expression of dri in the dorsal glia (arrow) seems to be unaffected in a stage 15 embryo mutant for pnt^D88. (E,F) Expression of dri in the dorsal glia is also unaffected in stage 15 embryos mutant for flb. (E) One focal plane, showing MM CBG, long arrow with asterisk. (F) A different focal plane showing the LG (short arrow) and the dri-positive neural cells (arrowhead).