Representative electron micrographs of Wt and 1/2-DKO specimen indicate accumulations of ELVs and high numbers of coated pits forming from the ELVs in ribbon proximity (radius r = 1 µm from the center of the ribbon) in the DKO after 15 min stimulation with extracellular solution supplemented with 50 mM K+. Scale bars: 200 nm. 