Fig. 1.

Four astrocyte-like glial variants in the medulla. a Schematic of glial subtypes in the adult Drosophila optic lobe. dmng distal medulla neuropil glia, eg epithelial glia, L1-L5 lamina neurons, La lamina, lmng lateral mng, Lo lobula, Lop lobula plate, mcg medulla cortex glia, Me medulla, mg marginal glia, Mi medulla intrinsic neurons, mn medulla neurons, pmng proximal mng, R1-R8, R8/R7 R-cell and axon subtypes, Re retina, sg surface glia, Tm transmedullary neurons, Xi inner chiasm glia, Xo or meg outer chiasm glia or medulla glia. R56F03-Gal4 (b) and loco ^1.3D2 -Gal4 (c) drive expression of UAS-cd8GFP (green) in ensheathing mng (e-mng) and astrocyte-like mng, respectively. R-cell axons were labeled with GMR-myrRFP (c, red), and glial nuclei with Repo (b, c, blue, arrows). d–n Single astrocyte-like mng were visualized using loco ^1.3D2 -Gal4 and UAS-FB1.1. Processes of dmng infiltrate medulla neuropil layers M1-M8 (d), pmng layers M9 and M10 (e) and lmng layers M7 and M8 (f). dmng visualized with volocity include long (g, h) and short (i, j) variants with stereotypic morphologies terminating in layers M8 and M5, respectively. dmng form microdomains in layer M5 (h, arrow). Asterisks in i indicate branches in layer M5 in a deeper focal plane. k Processes of single dmng (outlined) associate with 7–8 columns in layer M5. l–n Glial branches accumulate in the column periphery in layer M2 (l, arrowhead), evenly spread through columns in M3 (m) and aggregate in the column center adjacent to R7 axons in M5 (n). mng branches show a tiled organization (l–n). Processes of several mng converge into the same column (n, arrow, similar to microdomains in h) and marginally overlap (m, n, double arrowheads). R-cell axons were labeled with mAb24B10 (blue). Panels b–f, g–n show single optical sections, panels g–j show projections. For genotypes and sample numbers, see Supplementary Table 1. Scale bars, 50 μm (b–f), 20 μm (g–n), 10 μm (small panels b, c)