MG-derived RGCs recapitulate the visual projection pathway of endogenous RGCs. (A–E) Flat-mounts of wild-type adult mouse retinas treated with GFAP-Math5-Brn3b-tdTomato AAVs were double-immunolabeled with anti-tdTomato and anti-Tuj1 antibodies. The two areas outlined by the large and small squares in (A) are shown at a higher magnification in (B,C), respectively. Shown in (C–E) are representative images from the central, intermediate and peripheral retinas, respectively. (F,G) The optic nerves of mice treated with GFAP-Math5-Brn3b-tdTomato or GFAP-tdTomato (tdTomato AAV) AAVs were immunolabeled with an anti-tdTomato antibody and counterstained with DAPI. (H,I) Mono-ocular treatment of adult mice with GFAP-Math5-Brn3b-tdTomato AAVs revealed that tdTomato-immunoreactive axons projected predominantly into the contralateral optic tract. The yellow dashed lines in (H) outline the optic nerve and chiasm regions. The optic nerve from the uninjected eye (No AAV) is indicated. Shown in (I) is a higher magnification view of the region outlined in (H). Arrows in (I) point to axons crossing the midline of the optic chiasm while the arrowhead indicates a non-crossing axon. (J–L) The optic nerves, optic chiasms and optic tracts of mice treated with GFAP-Math5-Brn3b-tdTomato AAVs in one eye and GFAP-tdTomato AAVs in the other were immunolabeled with an anti-tdTomato antibody and counterstained with DAPI. The two areas outlined by the large and small squares in (J) are shown at a higher magnification in (K) and (L), respectively. Arrows in (K) point to axons crossing the midline of the optic chiasm. (M–T) Brain areas innervated by MG-derived RGCs in mice treated with GFAP-Math5-Brn3b-tdTomato AAVs. Shown in (N–P) are higher magnification views of the corresponding outlined regions in (M) and shown in (R) is a higher magnification view of the region outlined in (Q). AB, axon bundle; AOT, accessory optic tract; dLGN, dorsal lateral geniculate nucleus; DTN, dorsal terminal nucleus; EF, MG endfoot; MTN, medial terminal nucleus; OC, optic chiasm; OD, optic disk; ON, optic nerve; OPN, olivary pretectal nucleus; OT, optic tract; RGC, retinal ganglion cell; SC, superior colliculus; vLGN, ventral lateral geniculate nucleus. Scale bars = 320 μm (A,M,Q), 160 μm (B,F,H,J,S,T), 80 μm (G,I,K,N,O,P,R), 40 μm (C–E,L).