(A) Electron micrographs of RPE cells from littermate control and Vhl-cKO mice 3 days post Vhl deletion. Regions marked with perforated white rectangles are in the lower panels. Note the intracellular accumulations of lipid droplets (a; red) and glycogen (b). (B) Electron micrographs of RPE cells from littermate control and Vhl-cKO mice 14 days post Vhl deletion. Intracellular lipid droplets (a), extrusion of lipid droplets into the subretinal space (b), and lipids collecting along the basal laminar surface of Bruch’s membrane and between RPE basal infoldings (c) are observed. (C) Thickness measurements from electron micrographs and reveal that RPE hypertrophy occurs from 0–3 day post induction timepoints, and then plateaus from 3–28 timepoints in Vhl mutant mice (n=5). (D) Electron micrographs of RPE from Vhl/Hif1a (left panels), Vhl/Hif2a (upper middle panel), and Vhl/Hif1a/Hif2a (bottom middle panel) mutant mice 14 days post induction. Note that lipid droplets (dark gray spheres, upper left panel) and material resembling glycogen (small punctate spots) are observed in Vhl/Hif1a-dKO, but not in Vhl/Hif2a-dKO or Vhl/Hif1a/Hif2a-tKO RPE) 14 days post induction. These data suggest Hif2a is responsible for the phenotype in Vhl mice. (E) Choriocapillaris thickness values of Vhl-cKO, Vhl/Hif1a, Vhl/Hif2a, Vhl/Hif1a/Hif2a mice measured 28 days post induction (n=4). (See also associated Figure 4—source data 1 for panels C&E.) Scale bars=5 µm (A), 1 µm (A’a & A’b), 2 µm (B), 0.5 µm (B’a, B’b, B’c), 5 µm (D). Error bars represent mean plus s.d.