Neuropile glia that normally ensheath the pedunculus axonal tract require Ogre.
The mushroom body (MB) diagram on the left illustrates roughly where all of the optical sections shown on the right hand side panels come from - about 1/2 way along the length of the pedunculus. The entire mushroom body neuronal structure is almost completely enclosed by neuropile glia processes in wild type flies (Glia ensheathing MB structures: calyx, lobes, pedunculus). Neuropile glia are visualized by expressing UAS-mCD8:GFP (light green in A,C1,C2 and dark green in B,D1,D2) under the transcriptional control of the nrv2GAL4 (Sun et al, 1999) driver line. A, Optical cross-section through the pedunculus showing neuropile glial processes ensheathing the axonal tract. Axons of the tract are immuno-positive for FasII (red). B, Endogenous Ogre (red) protein in glial processes detected using an Ogre-specific primary antibody. C1 and C2, Pedunculus axonal tract (red) and glial processes (green) in two examples from an ogre mutant genotype. Glia fail to ensheath the axonal tract and some axons within the tract seem to be missing whilst others express variable levels of FasII - producing a spotty appearance. D1 and D2, Two examples of pedunuculus glia and axons in ogre mutant flies that express UAS-ogre in glial cells under the direction of the nrv2GAL4 driver line - effectively rescuing the glial ensheathment phenotype. White size bars are 10μm.