Immunogold labeling reveals the localization of PSV tonoplast aquaporin TIP3;1 and the 2S albumin and 12S globulin seed storage proteins to the EV in bent cotyledon embryo cells. A and B, Anti-TIP3;1 antibody labels the tonoplast of transitioning vacuoles. C and D, Anti-12S globulin antibody labels electron-opaque material accumulating along the luminal side of the tonoplast (C) and the entire PSV lumen in late-bent cotyledon embryos (D). E and F, Anti-2S antibody labels electron-opaque material accumulating along the luminal side of the tonoplast (E) as well as electron-opaque material in the vacuole lumen (F). OB, Oil bodies. Bar = 500 nm.