Figure 3. Caspase activation regulates the formation of autophagic network. (A–E) Electron micrographs of serum-starved EC exposed to ZVAD-FMK 50 µM (SS+ZVAD) or vehicle (SS) for 4 h. (A and B) Autophagic network (islet in A) with different maturation stages observed in serum-staved EC. Multilamellar electron-dense lysosomal bodies are also represented (white stars). White arrowheads indicate contact sites between AV. Scale bars: (A) 0.5 µm; (B) 2 µm. (C–E) Electron micrographs of EC serum starved with ZVAD-FMK 50 µM (SS+ZVAD) showing individual AV (islet in D and E) as opposed to large autophagic network seen in (B). Scale bars: (C) 0.5 µm; (D and E) 2 µm. (F) Mean number of contact sites per AV profile quantified for each condition; n = 30 cell profiles per condition; p = 0.005.